Parfit does give the right solutions to both his branchline teletransportation thought experiment but I have a more difficult time reconciling his response to the simple teletransportation thought experiment. Parfit seems to think that there is a justification for two responses to this experiment — one response saying that the person waking up on Mars is the same as the one that was on Earth and one response says that they are two different people. To me, Parfit’s psychological criterion of personal identity is met if you assert that the person who wakes up on Mars is the same as the one who left earth. Although objectively we may find that there is a gap in this person’s psychological continuity, to the person in question there would be no gap and it would feel only like a moment. Therefore, in the case of simple teletransportation, when the subject wakes up on Mars they would fit all three primary tenets of the psychological criterion and be the same person that they were before the teletransportation.
Parfit’s solution is correct in the case of the branchline teletransportation. His solution is both logically and intuitively correct; although it is posited as fitting the psychological criterion there are some aspects of his solution that seem to be in agreement with Olsen’s animalism theory that the human person is numerically identical to the human man; once the human man ceases to exist even if there is a human man exactly similar (like the person on Mars) the original human person would cease to exist. Parfit’s solution is also correct because the moment that each individual was created in their separate locations, they would begin to sense and perceive the world differently from each other. Once there was one human on Mars and another identical human on Earth, the two would cease having psychological continuity and cease continuity in the way they process sensations. What is seen on Mars would not be seen on Earth and vice versa. Parfit’s solutions for the branchline solution seems more intuitively correct whereas his solution for the simple teletransportation answer seems less so because of the idea of there being more than one correct answer.
Parfit’s views on personal identity are rather interesting. After reading Locke, Parfit’s modifications seemed to me to have corrected what appeared to be a somewhat flawed view. What I had trouble with accepting, was the idea that memory was primarily what informed one’s personal identity, since memory seems to be almost a necessary precondition of one’s personal identity. Parfit’s explanation of the ‘self’ is instead more appealing- it talks about the idea of ‘psychological continuity’ through time as constituting personal identity. He differs by saying that this conception of the ‘self’, of personal identity, is informed by a combination of psychological elements- opinions, external interactions and experience, intentions, as well as memories. This opinion seems a pretty rational way of looking at personal identity, so, for now, I would have to say that I agree with Parfit.
Parfit’s examples of the teletransporter, however, required me to ponder this assertion further. In both the simple and the branch line teletransportation cases, an issue that arose for me was the question of the transported person (Body B) being the same person as the original individual (Person A), i.e. having the same personal identity. Since there are two separate bodies, it is hard to say that both are the same ‘person’. Also, since the two are identical and have the same memories, beliefs, etc. at the time of transportation, it is also hard to assert that one of them is the original ‘Person A’. My conclusion was that neither of the two are the same as the original ‘Person A’. My reasoning was that since I could rule out the other two possibilities, what made the two bodies different from ‘Person A’ was the passage of time. As soon as the transportation occurs, the bodies are different because cells have changed, some have died, been replaced, etc. Also, with the passage of time, can come change in beliefs, intentions, etc. Therefore, unless we look at the state of the bodies and their psychological states instantaneously upon transportation, the fact that two separate ones exist, and are affected by time in different ways henceforth, neither can be Person A.
I think, when it comes to survival and our attitude towards death, this conclusion would make me disagree with the idea that we should regard this teletransportation scenario as the same as survival. Since the original ‘Person A’ body is destroyed immediately, besides that one instant upon transportation, the same ‘Person A’ survives no longer, and his trajectory of life henceforth will not be the same as if the original Person A had continued unaltered. However, I do agree with Parfit on the point that at the end, it really doesn’t matter whether A and B are the same as far as personal identity goes, or that I believe that it does not imply survival of the same ‘person’. Our memories and experiences and beliefs and everything of the sort will change inevitably over time, and so, in death, at the end, maintaining that idea of the same ‘person’ really shouldn’t make a difference.
I find Parfit´s Branch Line TT solution creative yet too simple. Though I am not very religious, I still believe that personal identity is somewhat related to the Cartesian idea of a soul, and for Parfit to dismiss this completely in his experiments seems to be an oversimplification.
If an identical copy of me was to be transported through some type of machine all the way to Mars by the click of a green button, with another copy still on earth, I think there would be some loss occurred by my original self. Parfit argues that the body B now present on Mars and body C now present on Earth, though identical, would lead different lives once they felt their first sensation. It seems to me, however, there is a loss of continuous identity. Being a person, and person hood is continuous, from the moment you are born to the moment you die. By creating two separate people, none of them would in fact be original to A by the time that they die.
Though Parfit refutes this argument by saying that personal identity is irrelevant, I have to disagree. It seems he uses a mathematical approach to something that is far from mathematical.
When I read Parfit, Wittgenstein just popped into my head. I don’t know if Parfit took influence from Witt, but their language and method are weirdly similar. “Criterion” has been a core idea of Wittgenstein. But here I want to talk more about Wittgenstein’s critic on philosophy itself, an approach I believe is also visible in Parfit’s thinking.
The strategy Parfit deploys is basically to dismiss questions like “Are A and B the same person?” as unimportant and valueless and thereby shift our focus to something else. Specifically he wants to downplay the idea of personal identity and highlight the notion of psychological continuity. If Wittgenstein were to comment on Parfit’s method, he would probably agree with it, but push Parfit’s idea further and say that the question of PI is an illegitimate philosophical question whose illegitimacy needs to be clarified by philosophy.
In what way can the question of PI be an illegitimate question? Parfit goes along the way to say that what matters is the fact, and after all the objective facts are clear, the question of PI – as I would further interpret it – is only a matter of how we translate the facts into subjective concepts we feel comfortable with, such as the very concept of personal identity. I believe for Parfit personal identity is less a factual question than a VALUE question, which is not of matter of truth but that of choice.
Buddhism has similar claim that personal identity or the notion of a self is nothing but an illusion. What’s more, it’s one of the many concepts coined by human beings that brings only confusion and ignorance. To achieve enlightenment one has to get rid of the notion of self. So I believe Parfit is not alone to argue that concept of PI should not be that important to us thinking beings.
Does Parfit give the right solutions to his simple and branch-line teletransportation thought experiments?
In his teletransportation thought experiment, Parfit suggests that if reductionism is true (that is, there is no “Cartesian ego”), then it follows that persons are indeterminate. So the answers to the question “Is replica on Mars the same person as the body that went into the teletransporter on Earth?” can be yes or no, and it doesn’t actually matter. I found his solution rather unsettling because his theory indeterminacy of personal identity only holds true if reductionism is indeed true. However, whether there is “Cartesian ego” remains unresolved. Does personal identity merely consist in nothing more than certain impersonally describable facts? Are we nothing more than a brain, a body, and a set of interrelated physical and mental events? I doubt.
I may be digressing a bit, but I believe that how a person actually comes into being in both the spatial and temporal sense is highly relevant when we think about his/her personal identity. Let’s consider the following analogy: suppose I make a replica of Leonardo da Vinci’s Mona Lisa out of an advanced photocopier so that the “original” masterpiece and the replica are exactly and qualitatively identical. Can I then say that the two paintings are the same? They are identical in many ways, but I cannot seem to convince myself that those two paintings are fundamentally identical. One of them is a masterpiece painted by the world’s most famous artist while another is a qualitatively identical replica produced out of a photocopier. One is a work of creation and another is a result of replication. Their history – or the way they came into being – are in no way the same. Therefore, I would not conclude that those paintings are the same.
Should we care if the qualitatively identical paintings are the same? Does it matter? I guess it does; otherwise Mona Lisa would have an estimated value much lower than the current $760 million. Likewise, I believe it matters whether body A on earth is the same as body A on Mars. Perhaps we should go back to his theory reductionism and question its validity. To deny there is no soul or anything of that sort is a hasty conclusion. To say it doesn’t matter is nothing but an easy way out.
I find flaws in both teletransportation cases posed by Parfit. In the simple teletransportation situation, in which the original body of person A is destroyed and his brain states are replicated into a new body (which occupies a different time and space) called Body A, it is expected that this new body is person A’s. That is, the brain state composition is replicated in its entirety and the person on Mars is numerically identical to the body that WAS on Earth – and this I think, is a key part of the argument: since the original body was destroyed, there is no choice but to believe that the new body that A’s brain states now occupy (Body A) is the same person as A. After all, if one body is destroyed and another created, the “number” of possible A-persons remains one. There is no overlap in the lives of original A and his Replica. The branch-line teletransportation situation introduces the problem of duplication and a violation of Parfit’s own “uniqueness clause.” This conflict occurs because in this scheme, a “blueprint” of the body is taken and preserved in Body B on Mars, while the original body is maintained but apparently defected, referred to as Body C. Now Parfit is quick to say that Body B and Body C are not the same person as A, and if one were, it would violate the condition of uniqueness that is assumed. Now the “number” of possible A-persons is two, and how can one person be two people? Plus there is overlap between the original A and its so-called Replica Body B – but this raises problems like, “Who is Body C?” and “If they overlap, are they different people or merely the same person with strong psychological connectedness?”
To believe that the Replica after simple teletransportation is the same as his original would be to assume that the process, though decidedly destroying the original body, successfully replicated a numerically identical A on Mars to the A on Earth. But when faced with branch-line teletransportation and the problems of personal identity it poses, it’s tough to say – if teletransportation worked and created a successful replicate in the first situation, it should be able to create a successful replicate in the second. So then Body B would be A, and Body C would be… no one? If you reject that simple teletransportation would produce a Replica that is actually A, you would thus reject that branch-line teletransportation could perform such a feat – perhaps the original person is destroyed, and no one is A now. But can Parfit’s teletransportation thought experiments be rejected due to just the duplication problem, or further because personal identity is more than just the arrangement of bodily cells and brain states?
While I do think that Parfit’s perspective helped bolster Locke’s original argument on personal identity, it appears that there is a great dissonance between his thought experiments and his explanations behind them. Parfit questions Locke’s view on the dependence of the recollection of old memories on a person’s existence, and rather posits that there only needs to exist a continuous chain of memories between person X and person Y to be them to be the same. Moreover, Parfit’s takes into consideration other psychological connections in the event that memories cannot be preserved, such as beliefs, intentions, and goals. This notion of psychological continuity was a nice addition to explain cases where memories cannot be recalled due to physiological impairments.
I also agree with Parfit regarding the indeterminacy of personal identity, as exhibited in the teletransportation thought experiments. I found it paradoxical but quite effective for Parfit to present the teletransportation thought experiments as potentially exemplifying the “uniqueness condition,” while simultaneously disproving the condition all together. I can posit that the person on Earth and the person on Mars are in fact the same, provided that both persons become incapable of receiving new stimuli or suddenly die before gaining consciousness following teletransporation. There should indeed be a moment during which divergence has not occurred, thus making the ephemeral existence of person Z as psychologically continuous with Y possible. I also also argue that one’s social and physical environment is integral in shaping one’s personhood, and since no two persons can be at the same place at the same time, the same psychological continuity should not be possible among two persons. Parfit successfully showed with this experiment how indeterminate personal identity can be.
Does Parfit give the right solutions to his simple & branch-line teletransportation thought experiments? Why/why not?
For the branch-line teletransportation, I too don’t understand why body A and body C (that one that stayed on Earth) are two different persons. Nothing happens to body A, except for an exact replica of it is sent to Mars. This is no different than like mentioned, getting an MRI, going through an airplane security scanner, taking a shower? I think I might be misunderstanding the “uniqueness condition.” Parfit is saying that the branch-line violates the uniqueness condition. Wouldn’t it not be violating it because body C is basically body A, and body B is not psychologically continuous with body A?
And in the simple teletransportation thought experiment, I am caught up with frustration. Parfit’s response is that it is indeterminate whether body B is person A, and why should it matter? But is the physical matter the same that makes up the new body B? Or was that matter destroyed and body B is made out of new matter. Because if that is the case, I wouldn’t think that they are the same, but then again I guess it doesn’t matter! I keep going back to what Andrew said in class about how given the opportunity, he wouldn’t go through with this simple teletransportation, and I feel the same. So I guess my real issue is that I am holding on to the idea of a soul, and then I ask myself why? Why do I feel so connected to my body? If reductionism IS true, then I think the value thesis makes sense. But the fact that I wouldn’t go through with this teletransportation makes me feel that reductionism can’t be true.
While I agree with many of Parfit’s points, especially his ideas about psychological continuity, I find myself somewhat at odds with his interpretation of simple teletransportation and completely against his ideas about branchline teletransportation. I will begin with simple teletransportation. Here, Parfit says that it is indeterminate whether the body that emerges on Mars is the person who entered the transporter on earth. Initially, I felt strongly that the body on Mars must be the same person because the narrator of the story experiences a fluid transition. That is, person A was writing the story on Earth and when he woke up an hour later on Mars, the narrator was the same and continued his story. After further thought however, I realized that by nature of the inherent psychological continuity, it could be a new and exactly similar person on Mars. This person would remember writing the story as if he were the author, and would thus continue writing as if nothing had changed. Where I disagree with Parfit is that even though it is indeterminate whether body A is person A, I think this is very important while he thinks it does not matter. Parfit wants to say via reductionism and the value thesis that it is irrelevant whether you or someone exactly like you emerges on Mars, but I disagree. I am fully aware of myself as a thinking entity, and if it is merely a perfect copy of me who emerges on Mars, then I would cease to exist upon using the transporter. There would of course be a perfect clone of me who emerged on Mars, and the rest of the world would not know the difference, but I would be gone.
I have several problems with Parfit’s interpretation of the branchline case. He says that neither body B nor body C is the same person who entered the transporter. I disagree with this interpretation. In terms of the uniqueness condtion, what Parfit reasons seems to make sense. However, when you think about the details of what his interpretation implies, it begins to seem ludicrous. In the branchline example, you would walk into the machine and it would scan you but leave you intact. Based on what Parfit says, the second this machine turns on, you are somehow no longer you. This does not make any sense to me. If someone takes my photograph and says they can use it to make a perfect, psychologically continuous, clone of me, taking my photo does not suddenly mean I’m no longer me. I know that I am still the same thinking entity, and nothing has changed. Thus, the body that walks out of the machine on earth is the same person who entered, and the body on Mars is merely a perfect clone. It follows that the value thesis, where having a heart attack while your clone lives on is about as good as survival, seems silly to me. If you have a heart attack and die, the thinking entity that you are is still very much dead no matter how many identical clones you have living on Mars. Thus, having a clone live on instead of you is very different from survival, even if the rest of the world can’t tell the difference.
In answering the above question, it is important to note the distinction between giving the right solution–that is, the logically sound solution–to Parfit’s experiments given his assumptions and giving the solution that we want believe is the case. Parfit’s reasoning works in a framework that is supported by several premises and definitions, including the definition of psychological connectedness and continuity (which he defines, arbitrarily, as over 50% connectedness), the psychological criterion of existence, and relation R. He also assumes that there is not a Cartesian ego, among other assumptions. These premises and definitions could be debated, but that will not be the purpose of this post. Instead, this post will argue that Parfit is correct in his solutions to the simple teletransportation (STT) and branch-line teletransportation (BTT) examples within his logical framework.
Given all of his definitions, it is indisputable that after STT the facts do not lead to the logical conclusion that the person on Mars must be either numerically identical or qualitatively identical to the person who was destroyed on earth. Rather, the facts leave open the possibility of both. The facts are that the person on Mars will be physically exactly similar to the person on earth and will be fully psychologically continuous with the person on Earth. As Parfit says, the replica on Mars could “be me” or it could be “someone else who is exactly like me” (447). There is no way to determine which one of these is the case. Parfit argues that in order for these hypotheses to compete, we must accept some further qualification of existence, something like the Cartesian ego,or a mental, non-extended substance. Parfit’s reasoning seems to be perfectly sound, and I would agree with him here, even though the result seems non-intuitive.
As for the BTT case, I think Parfit is also right, given his premises and definitions. Parfit’s claim is that the two people–the one on Mars and the one on Earth–are qualitatively, but not numerically identical. This makes sense since they are both physically qualitatively identical, and both have relation R to the original on Earth. Since neither is unique, however, personal identity is not preserved since PI = R + U. But, according to Parfit, that is not what matters, so this case of division should be regarded as “about as good as ordinary survival” (449). Although double survival is not the same as ordinary survival, it is not the same as death. I would have to agree with Parfit here, once again, even though the result might seem a bit unsettling.
I would like to respond respectfully to the point that Evan Gallagher made in his post that “[w]hat we’re looking for in a theory of personal identity, I think, is confidence, and there is nothing here to inspire confidence.” I think that everybody is entitled to their own view of personal identity, based on what they want to get out of that definition. For me, however, this discussion of personal identity is not about inspiring confidence, it is about discovering the truth about personal identity. If it turns out that Parfit is right, and that there is no determinate way to say whether or not we exist after teletransportation, can we dismiss this conclusion on the basis that we don’t like it since it doesn’t inspire confidence? I think that it is is misadvised to go about searching for a theory that will fit a particular need. To do so would be to confuse the positive with the normative. As Gretchen Weirob argues in the Miller dialogue, there is some unalterable, true fact about the matter, and our societal conventions about the personal identity do not change its true nature.
Parfit states that if reductionism is true, it follows that persons are indeterminate in the question “Is person X the same as person Y?” does not have an unique correct answer- it can sometimes be correctly answered in either way. In the case of the simple teletransportation example, Parfit suggests that Body B is not necessarily the same as person A. I find this problematic in that there are many actual cases similar to simple transportation such as sleep or being in a coma. Would Parfit say that we are not the same persons when we awake from sleep as when we went to sleep?
In the branchline example, I believe that the person follows the consciousness. I think it is significant that when he awoke, his conscious remained with Body C. Therefore he remained consciously continuous with person A. But then what happened to Body B? Well, I agree with Parfit when he says, who really cares? Both Body C and B may be consciously continuous with person A, but this does not mean that they are consciously continuous with each other. So, if the consciousness splits in two, where does the person go? Although it may seem like the easy answer, but I agree that, because the person had to choose between two bodies, it is indeterminate.
Even though the question of “Is person X the same as person Y” indeterminate in the branchline example, I think that Body B is person A in the simple teletransportation example. This is because, in the simple example, the person remains in one body and does not face the problem of being in two places at once. Rather than having to choose between two bodies, the person definitively transfers to one body, which does not violate the duplication law.
Parfit successfully modifies Locke’s psychological argument by (a) allowing for overlapping chains of psychological connection/continuity of experience, and (b) broadening “psychological connections” to include beliefs, desires, intentions, goals, hopes, etc, in addition to memory. In this way, he fixes the amnesia, transitivity, and duplication problems.
In response to the simple teletransportation thought experiment, Parfit essentially says it doesn’t matter whether person A (on Earth) is the same as person B (on Mars), and if you are wanting to give a yes or no answer to whether they are the same or not, you believe in a soul or “Cartesian ego”. In the branch-line scenario, he says neither B nor C is the same as person A, and that B and C are qualitatively, but not numerically, identical. I agree that B and C are not the same person—although they originate from the same person A, they form new experiences independent of one another, making them different people (except for maybe the split second when B and C are both created and haven’t formed separate experiences yet). Parfit says B and C are not the same because this would violate the uniqueness clause. Perhaps I’m misinterpreting this part of Parfit’s argument, but this seems contradictory given that he later states that uniqueness doesn’t matter. Setting that aside, after thinking about Parfit’s overall view, I agree with him.
At first, I found it hard to let go of the uniqueness (U) component, which Parfit deems irrelevant, in his equation PI = R + U. At first glance, uniqueness seems to be so central to what we call personal identity—how could Parfit deem it so unimportant? However, once I thought in terms of Parfit’s reductionist side, I let go of this idea and actually felt relieved, and even comforted by his theory. The “my division” example makes sense to me—there is psychological continuity between A and B, and A and C, and this is all that should matter. PI should depend only on my own psychological continuity (intrinsic), and not the extrinsic relation of uniqueness—just R is enough. It feels strange to set aside the idea of the soul, but it restores my comfort knowing that I will live on through psychological continuity in some other body after I die.
I believe that Parfit gives the right solutions to both thought experiments based on his view of personal identity. He gave the equation of personal identity as PI= R + U with U representing uniqueness and R representing the relation of psychological continuity. According to this equation, it is indeterminate whether the body (A) that enters the portal is the same as the body (B) that exits the portal in the simple thought experiment. We know that R is constant from body A to body B because the consciousness of the person who entered the portal is completely copied and transferred. Can we say that the person is still unique though? One could argue yes because the body is a complete replica or one could argue no becuase even though a replica was made, the original body was destroyed. We also see a correct solution based on his perspective of personal identity for the branch line thought experiment. Although his solutions do match his criterion for personal identity, I don’t agree with Parfit’s solution to the experiment. He presents personal identity as a combination of continued consciousness and a form of animalism. I believe uniqueness is not needed to define personal identity. I believe the relation of psychological continuity is all that is needed. I find more agreement with his value thesis. Uniqueness does not matter. What matters is the continuation of one’s thoughts, beliefs, morals, emotions, etc. Where Parfit and I differ is that I believe that this continuation of consciousness is all that is needed to define personal identity while Parfit believes that uniqueness still plays some role in defining PI.
I think Parfit does give the correct solution to his simple and branch-line teletransportation thought experiments. However, I still find it pretty difficult to say I would press the green button and send a copy of myself to Mars. There is something inherently distasteful about this idea to a human being—the thing that wakes up will not be me, despite the fact that it looks, walks, talks, acts, and thinks exactly like me. And, because I do not believe in a Cartesian soul, Parfit is right to say that there is an intrinsic contradiction between my professed beliefs and actual actions/desires. Parfit uses his teletransportation thought experiments to prove that personal identity (specifically uniqueness) does not really matter—if the relation R (psychological continuity, continuity of experience) defines most of personal identity, the fact of survival is clear in both thought experiments. So, even when his uncopied body expires and his identity dies, he concludes that in a small way his experiences continue through affecting how alive people think. While this view has apparently liberated him from his fear of death, I can’t say I’ve gained this same benefit.
I am still slightly confused about one aspect of Parfit’s conclusions. Considering the branch-line case, let’s call the original person on earth person a, the person that steps out of the machine on Mars person b, and the damaged original person c. It is clear that person c is the same as person a—they are psychologically and physically perfectly continuous. Parfit makes it similarly clear that person b is the same as person a, and I accept this part of his argument. However, I wonder if Parfit would claim that person b is the same as person c. Persons b and c are strongly directly connected to person a, which defines a link in Parfit’s overlapping memory chain—but at what point do they become different people?
Parfit’s teletransportation story poses some very interesting and convoluted problems for conceptions of personal identity. Although it seems more complex at first, the branch-line case, involving a copy of the narrator, is perhaps the better place to begin examining Parfit’s arguments.
In this situation, an exact copy is made of the narrator, who remains alive, whole, and conscious on earth. According to Parfit, a personal identity requires both psychological continuity (going from his own definition, a modification of Locke’s) and uniqueness. In light of this, it seems that he would say that Person A ceases to be the instant that body B is created and C walks out of the teletransporter. Given the rationale that the two bodies are indistinguishable and have all the same memories, it doesn’t make sense to say that only one of them is person A, and both of them obviously can’t be. We are forced then to concede the rather strange third option that neither of them is person A. I am willing to accept this with a few constraints, which I will talk about later, but I am still left with the question of, when body C succumbs to a heart attack, does body B then become person A, or do they remain their own separate person? In essence this is the same question that is posed by the simple teletransporter case. In both, whether hours later or days, the original body that stepped into the machine is destroyed, and there is a single body left on mars.
In the end, one’s interpretation of this result relies on their beliefs about the metaphysical nature of the world. I myself follow the animalist school of thought. Therefore, it is inconceivable that the body on mars truly is the identical person that stepped into the machine and pressed the green button, since the person and the body are one and the same. Nevertheless, a person is left who believes, and whom society believes, to be the same person. In the grand scheme of things, in the absence of an enduring soul, all the remains of a person is the influence that they had on others and the world around them. Therefore, I find myself in agreement with Parfit that it doesn’t really make a difference whether the new body is you. If it is, all the better; if it isn’t, you’re gone for good so you won’t care, but the net effect on the universe will be the same as if it were.
At this point I’m definitely not ready to reject either of the conclusions that Parfit draws from his thought experiments. That being said, I am a little wary to accept both of his solutions wholeheartedly because I think that there are some inconsistencies in his argument. He starts off very carefully defining personal identity, psychological continuity, and psychological connectedness. I was happy reading this part because introducing/ redefining these terms patched up some major holes in Locke’s argument. After reading the simple teletransportation scenario I was quite convinced that the person who came out of the machine on Mars would essentially be the same person as the one who entered the machine on Earth. With the transitivity problem solved, I couldn’t think of anything important that the person on Mars would have that the original person hadn’t.
Like most people, I was a little more uneasy when Parfit proposed the Branch-line teletransportation scenario. But having already accepted the continuity between the two men in the simple scenario, I couldn’t think of how to refute the idea that the branch-line original would survive as two. If one person survived in the first scenario, then why shouldn’t two in the second? Psychological continuity seems to be something that is so personal; I cannot imagine how it could be compromised by the existence of a clone millions of miles away. Even so, it is hard to accept the “deeply impossible” notion that a stream of conscious could be split into two.
Although I can logically accept most of Parfit’s argument I was confused and a little troubled by how he ended by explaining away the importance of “uniqueness” to personal identity. When I read over the first part of the article again I was struck by how carefully (and sometimes arbitrarily) Parfit defined psychological continuity and personal identity in order to make sure he could take care of the transitivity problem. To me, it seems strange that he patched up that hole so neatly and then kind of danced around the uniqueness problem. As a philosopher, I think Parfit should be allowed to define personal identity any way he wants, but I am distrustful of the inconsistency with which Parfit treats these two problems. Intuitively, both problems seem to be equally substantial threats to Locke’s theory of personal identity. I guess I’d say that, like most philosophers, Parfit’s argument is sound based on the criteria that he has set for it, but I don’t think that it offers a perfect, or even a completely satisfying, interpretation of personal identity.
Parfit’s simple teletransportation thought experiment initially resonated with me, and I was very inclined to say that the individual on Mars and the individual who pressed the button on Earth would be one and the same. However, his branch-line teletransportation argument quickly made me realize how problematic this view was. I believe Parfit has hit upon something essential and important with his concept of psychological continuity, which is both intuitive like Locke’s theory, and stands up much better against critiques such as amnesia, vegetative states, and even simple sleep. I believe Parfit’s psychological continuity truly is an essential part of identity, and he correctly applies this theory to both situations. I believe he is absolutely correct in his statement that being qualitatively identical is not equivalent to having the same personal identity.
However, I am not completely inclined to agree with his entire equation of personal identity: PI = R + U. Specifically, I would like to challenge his inclusion of uniqueness (U). While I cannot think of a good counterexample to specifically refute U, it leads Parfit to conclusions I am not comfortable with. Because he concludes that neither person/body produced in the branch-line scenario (B and C) is identical to the original person (A), the death of B or C is essentially a nonissue, as the survival of the other is “about as good as ordinary survival.”
Imagine the branch-line scenario occurring exactly as Parfit has described. The individual on Earth (let’s call him C) is told he will die in the next few days of heart failure. Now, imagine a doctor comes rushing into the room and says, “We’ve just revolutionized a new procedure that will fix the heart malformations caused by the teletransporter! We can save you!” Should C accept the procedure? Parfit claims that C’s survival is largely irrelevant. Yet, it seems obvious that C should leap at the chance to have this procedure performed, as it will extend his life another 40+ years when before he was certain to die within the next few days. Thus, I am not convinced by Parfit’s conclusions.
I propose replacing U in Parfit’s equation with M, where M is matter continuity. Matter continuity is similar to psychological continuity in that M = “there are strong overlapping chains of strong material connectedness between X and Y,” thus allowing for the slow recycling of matter within in an individual without claiming a new person has been created.
Now, instead of claiming that the simple scenario results in an indeterminant result, we may comfortably claim that the individual on Mars is a new person (explaining many people’s intuitive qualms about pressing that button), while C on Earth is the same person because he has both psychological and material continuity (R + M). C’s death would essentially be a sacrifice of his own life to create a new person, which he may not be enthused about. If we can save him, we should, because B’s survival is not as good as his own survival. This is in line with my hypothetical “doctor scenario” – he should accept treatment.
Parfit’s thought experiments raise the question of self identity in an uncomfortable and initially far-fetched scenario. In the simple teleportation scenario, personB comes into being on Mars after being physically destroyed on Earth. If we let go of the idea of the cartesian immaterial mind, then Parfit’s logic and solutions make sense. If I lose consciousness and wake up on Mars with the same body and the same memories and thoughts–I must be the same person. Even if I have not come into existence in the same way as my Earth body, there is no physical previous me so this personB is all there is of my physical and psychological self. My energy cannot be created or destroyed, so personA being transferred in a different form and reassembling into personB is no different than how our cells are going through death and life cycles. The relation continues and therefore I continue.
As others have mentioned, Branch-line is more complicated and harder to accept. I agree with Annie’s point that the knowledge that your replica exists disrupts the continuity of consciousness and makes the replicas have different future experience. I initially thought of this as if twins were separated, both were given the same genetic code and both would have the same slate of psychological experiences. Once there are two, they cannot be the same. However, I also questioned if the replica did not know the original existed and then the original dies of heart failure, the replica is basically the same as the replica in the simple tele transportation problem. I guess what I have trouble with is that hypothetically in the simple problem, the person’s own energy could be transferred to this personB but with branch-line there are two different people made up of equal but different energy. Maybe I misinterpreted. Regardless, I would agree with Parfit that if all my parts and my psychological self were reassembled somewhere that is survival of myself and my genes. My could be me and would be able to pass down who I am. Maybe it really does not matter.
Parfit’s telentransportation scenarios were very thought provoking- very bizarre to try to imagine as a real-life possibility. At first, the scenarios were slightly repulsive to me. I did not like imagining this type of world, where peoples’ bodies were destroyed and put back together. Just imagining a world where living beings could be synthesized using technology was hard to wrap my head around. But after putting some thought to these ideas, I have found that I agree with Parfit’s solutions to the simple teletransportation thought experiment. What I believe is most important to identity is continuous consciousness, or at least perceived continuous consciousness. I agree with Parfit that this relation, or “R”, does not have to rely on memory, but instead a psychological connection that can be made up of intentions, beliefs, or desires. In the scenario of the simple teletransportation, this psychological connection is upheld, and so is the perception of continuous consciousness. Even though the body that enters the teletransporter is destroyed, they have a psychological connection with the person that entered the transporter- they have a perception that they only lost consciousness for a moment and awoke unchanged, just like the experience one feels when awaking from anesthesia after undergoing surgery.
However, Parfit’s branch-line teletransportation thought experiment, and his conclusions, were much harder for me to comprehend. The idea of having two of myself living at once is unsettling, and after considering this example, and Parfit’s conclusions, I did not quite know what to think. The first conclusion I came to was that these two people could not the same person, because their streams of consciousness are different. The moment they begin to have different experiences, memories, and psychological connections, I don’t believe they could be the same “person.” However, we are never really told what the person who came out on mars is experiencing. Perhaps that person will still have all the experiences of the person who entered the teletransporter, and that person will have an uninterrupted stream of consciousness. Did they realize something went wrong, and that there was still another one of “them” on earth, or do they go on living their life, just as they had every other time they used the teletransporter? If they never realize that there is another “them” still on earth that will die in a day or so, then they are essentially still “themselves”. In this sense, I agree with Parfit that the uniqueness clause is relatively unimportant compared to R. As long as someone is experiencing a connected psychological experience, there is really nothing else that matters. Even they did find out that their previous body were still living on earth, that really does not change the fact that they are living a psychologically “connected” life. In the end, does it matter that there is another “person” that resulted from the same original being? Just like in the “My division” scenario brought up by Parfit, I believe that both resulting beings can originate from the same one being, and both be continuous with that previous self, yet from that point on differ. And in the end, ass weird as it is to say, I think I agree with Parfit that nothing really matters except a connected psychological consciousness, a relation “R” between beings.
Considering that Parfit works from a base of the brain without some sort of mind/soul substance, I think that he does arrive at the strongest solution to his problems, for the most part. In both the simple and branch line experiments, he questions whether personal identity can survive situations in which information is transferred to different matter in order to rebuild the person. This is important, because in his argument even psychological things (ie memories and beliefs) are rooted in the physical. They’re not exact pieces of matter, but rather states or patterns in which the matter behaves. Furthermore, at the most basic level, there is no difference between the matter in inanimate and the matter in living brains. Taking this into consideration, it seems that the branch line experiment is not even completely necessary to arrive at his final conclusion regarding R and the absence of a personal identity as we like to imagine it.
The key to the strength of his conclusion is that, in reality, we change. The atoms in our bodies, our beliefs, our thoughts, even the subtle connections between neurons change with every thought. The fact that we persist over time means that we must change, or else it would essentially be the same as not moving forward with time. Yet, this constant change is no different from the teletransporter in Parfit’s experiment. This actually reminded me of something Descartes mentioned in his Meditations. Descartes stated “because the entire span of one’s life can be divided into countless parts, each one wholly independent of the rest, it does not follow from the fact that I existed a short time ago that I must exist now, unless some cause, as it were, creates me all over again at this moment, that is to say, which preserves me” (III.49). In this case Descartes is referring to God, but there could be some sort of cosmic teletransporter that constantly recreates everything at each “now point.” It is the information exhibited by the matter, not the matter itself that is important. Yet that information/behavior (that becomes the psychological aspect of a person) still relies on the existence of matter, so it must change too. There cannot be an unchanging essence, so there numerical identity cannot persist over time.
On a somewhat related note, yesterday there was a lecture given by Fusan Ryushin on the Buddhist concept of death without the self, and he used a metaphor that seemed somewhat relevant to the issues we were discussing in class. If the universe was a sheet of cloth, then each person would be a tiny section of the cloth that twisted around itself until it seemed to become somewhat of a separate entity (and in our case have awareness of that existence). Yet, the twist is still part of the cloth and there is no difference in material. On a practical and everyday level the twist does become an entity of its own, but on a metaphysical level it is no different from the cloth. If the twist were recreated elsewhere, it would still be just as good as the original twist ‘surviving’ and if the twist unraveled, it would still exist, just in a different state.
I basically agree with Parfit’s answer to both the simple and branch-line teleportation cases. I especially think he is correct to assert that rather than numerical identity, it is relation R (the relation of psychological continuity) that we should really be worrying about. However, in some ways I think I am willing to go even further than Parfit, and say that not only should we not be worrying about numerical identity, the reason we shouldn’t be worrying about it because it doesn’t exist. I don’t think it makes much more sense to posit a psychological criterion of personal identity than to posit an animalist criterion of one — although I do think the psychological criterion gets us closer to the relationship we tend to THINK of as identity in the normal course of affairs, namely that between our present and past-future selves. However, I don’t think this concept answers to anything meaningful — like Parfit says, the only possible way it could would be through some vestigial dualism. For anything to endure, constant and unchanging, from one moment of our experience to the next, we would have to posit some sort of substantial Cartesian ego; a solid, first-person audience member sitting in the theatre of the mind. I don’t find this a plausible picture. None of the things that seem to make us up — sensory data, experiences, mental representations, bodily states — can be identified with this homunculus. The locus of our I-voice unfailingly eludes us; at least, this has been my experience whenever I’ve tried to look for it (in meditation, or sometimes in artistic activity). In fact, in my experience, I don’t think that the sense of being a first-person is usually present with any constancy at all. Usually there is just experience; just the psychological content itself. (It seems to me like the concept of an I-voice only emerges when this psychological content turns in on itself and starts processing itself on a meta-level. But I digress.) Anyway, if we accept this chain of reasoning, all that we are left with is the content of experience itself (and the physical state which is somehow identical or related to this content — but this is kind of a black box right now, so I’m not going to try to open it yet). It seems undeniable, to me, that these mental contents are constantly in flux. The same is true of the body they correspond to: our physical organism is constantly recycling its parts and reconstituting itself with new ones. Thus, my mental-physical state in one moment is as different from that state in the next moment, as, say, two different frames in a time-lapse weather simulation.
Following this argument, I agree strongly with the paragraph on the Bundle Theory which was included on our in-class handout. Replication is ‘about as bad’ as ordinary survival. Relation R is, essentially, the relation we hold with our past and future selves, and there is no special extra ingredient or ‘further fact’, beyond continuance of psychological state, that we are referring to when we talk about being the same person today as yesterday, or when we were five. Personhood is a similarity cluster rather than a numerical entity. Thus it doesn’t matter whether you have one copy or two copies or whatever — none of them will be you, of course, but ‘you’ wouldn’t have been you either.
I do believe that Parfit gave the right solutions to his teletransportation thought experiments.
The branch-line teletransportation (BT) offers a fairly straightforward solution, at least to me. It seems quite clear that because there are two bodies that originated from the same person and exist at the same time, they cannot be identical. The moment that Person B walks out on Mars and Person C walks out on Earth (both originating from Person A), they become different people and therefore have different identities. As soon as they start having experiences and creating memories independent from one another they are distinctly different. They do not share any sort of psychological or physical linkage; one does not feel pain when the other is pinched. They therefore cannot be identical because they are not continuous in any sense after they start taking actions and thinking thoughts independently of one another. Parfit says that they are not identical because this violates the “uniqueness condition” that he has presented, and I would agree.
The simple teletransportation (ST) case is not so clear-cut. A person on Earth is copied and then reproduced on Mars, after the original body on Earth is destroyed. Are these two people identical? The instinctual answer is to say no. The body that was created on Earth by a human mother (supposedly) has been destroyed and then recreated somewhere entirely different. If we think about origin as one of the things that defines identity, then this would violate that. I understand how this process could be a bit disconcerting. It is unnerving to think about your body being destroyed in one place and then somehow reappearing, in the exact form, somewhere else. The same, but most certainly different. Parfit argues that the answer to this case would be indeterminate, meaning that the people could be identical or not, and I would agree with that. He argues that it does not really matter what the outcome of the situation is because what really matters is psychological continuity. Parfit even says that personal identity does not hold any weight against psychological continuity. While I do agree mostly with that, I would also not be so quick to dismiss certain aspects of our identity. I do believe that humans transcend their bodies but I believe that the ability to transcend has to originate from our bodies – our unique bodies. And so then I am tempted to say that in the case of ST, the person who entered the machine on Earth would be the same as the one on Mars because although the body itself does not have the same origin, it is still physically exactly the same. And the person would still be psychologically continuous. It would be more problematic if the person left on Mars in a different body. Then I would argue that they are not the same, even though the person on Mars would still be psychologically continuous with the one on Earth. I think, then, that there has to be some sort of interaction with body and mind and so while I am not completely satisfied with Parfit’s theory about the self, I think he has offered the closest solution to what I believe to be the definition of self and personal identity.
Parfit offers a surprising solution to the questions brought up by his teletransportation experiment. Where many other philosophers try to parse out this seemingly unanswerable question, Parfit goes the next step, by leaving it unanswered rather than struggling with it. When it seems plausible that there would be more than one “you” surviving the branch-line version of teletransportation, Parfit suggests that it really doesn’t matter which one of these is the real you. His arguments are logical in describing the resulting bodies, and it is hard to definitively argue one way or the other. Even in the main line teletransportation, which seems like it would be “you” on the other side, there is a gap in the continuity of time and space upon which we tend to define our existence. I think he is very clever in taking it the way he does, rather than trying to decide whether or not “you” still exist; he doesn’t try to argue for how we define personal identity.
As initially shocking as his declaration is-that personal identity doesn’t matter-after a letting it set in a bit, it starts to make sense. Really, all my life is is a series of relations, between my mind and body, my mind and itself, between me and other people. It makes sense then that I can define myself (which doesn’t matter) by this string of relations, whether or not they are continuous in time and space. The way we create meaning is in relation to the outside world, and so it is reasonable to think of this string of relations continuing after our “death” in a different manner. In the most physical way, my children will live on in relation to my life, as well as in the ways I’ve interacted with other people. So although this string is no longer anchored to a single physical being, it still continues. The actual “me” doesn’t matter, I am defined by the varied ways this mind and body I claim to inhabit interacts with the rest of what may or may not exist.
It does feel like a bit of a cop out though, similar to religion in my mind, a way to create peace of mind in face of our mortality. It marks an ill-ease at leaving this question unanswered, as I think it remains.
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
I disagree with Parfit’s solution of the branch-like teletransportation that neither the person who came out of the machine on earth (body B) nor the person who came out on mars (body c) is the same person as the one went in the machine at the very beginning (body A). Although his argument about the violation of the uniqueness clause sounds logical when applied to the bran-line teletransportation as one event, the argument does not really make sense if we consider this teletransportation as 2 loosely connected events: event 1 starts from body A walking in the machine and ends at body B coming out of the machine and event 2 starts from then to when body C emerges from on mars. Considering event 1 alone, we find it really hard to convince ourselves that body A and body B are different persons because event 1 is directly comparable to a scenario where a person gets in an MRI scanner and lies there for a couple minutes before getting out realizing there was something wrong with the machine. In this case, it is unlikely that anyone would argue against the fact that the person who got out of the scanner and the person who went are 2 different individuals. Linking this back to Parfit’s branch-line teletransportation, we can conclude that body A and body B are the same, contradicting Parfit’s interpretation.
There is an old economics joke that is particularly relevant in discussing Parfit’s arguments. An engineer, a chemist, and an economist, are stuck on a desert island, surrounded by cans of food, but do not have a can-opener. The engineer says, “If we jam a sharp piece of rock at the right angle, we should be able to pop open the can.” The chemist says, “That’s rubbish. By creating the right fire conditions and heating gently, we can open the cans and warm our food properly.” The economist says, “Let’s assume we have a can opener.”
This same vein of absurdity can be encapsulated by Parfit’s thought experiments, designed to challenge our deeply held conceptions of self. I believe that Parfit does make a mediocre argument for the simple and branch-line teletransportation, but only in his universe. What if the replicator accidentally places a single hair follicle astray? What if the replicant falsely remembers his 2nd grade math teacher as Ms. Johnson instead of the true Ms. Smith? Is there a strong enough psychological continuity for Parfit to declare that the two have the same personal identity? Parfit argues through his equation PI=R+U, that these small differences in uniqueness have little bearing on personal identity, but I would disagree. Does 98+2=98? No, of course not! Despite the magnitude of R, U still exists and negates his point, “ U makes no difference to the value of R.” (450) I believe this brushing aside to be a fundamentally naïve claim.
Our bodies move temporally through time and space, sloughing off some molecules and accumulating others. I imagine a worm eating its way through soft dirt at a constant rate. Parfit stipulates that if we stop this temporal streak, capture it instantaneously, and send it across the solar system, the same personal identity will emerge. This disjunction of being in time does not allow the replica to be inherently the same being. In the branch line hypothesis, when person A steps in and is scanned, person A does not emerge. This is due to the Heisenberg uncertainty principal that states we cannot know the velocity and the position of an electron at the same time. By observing all of the electrons in the body simultaneously, they are fundamentally altered and we can say the replica on Mars (B) and the scanned man on Earth (C) are each different from the man who walked in (A).
I believe that Parfit makes interesting and thought-provoking claims, but he forces the reader to makes leaps of faith against essential scientific propostions that would cause his argument to crumble.
Initially I agreed with Parfit wholeheartedly, accepting his argument for the Psychological Criterion to build upon Locke’s Memory Criterion. In the case everyday living, Parfit’s idea of psychological continuity seems to be more in agreement with what many people would naturally lean towards but perhaps not have the specific vocabulary to express (myself included).
Things get more complicated with the simple teletransportation (STT) example. There is something that is viscerally frightening about having one’s body destroyed even if survival is guaranteed. Yet, listening to Parfit as the narrator describing waking up on Mars is reassuring; the logic of psychological continuity remains intact and expresses its relevance.
It is the branch-line teletransportation (BTT) example that forces one to reconsider these last thoughts and reevaluate the nature of the transportation Parfit is suggesting. How can one version of a person be teleported to Mars, while another remains on Earth? My interpretation of this dilemma is that the Earth body (EB) is the original, or true “person” while the Mars body (MB) is the product of an accelerated birth –a being is created who is analogous to the original yet in reality this being only came into existence within the milliseconds it took to rearrange formerly inanimate matter. The MB may look back in its memory and think, “I was teletransported to Mars and this is how I came to be standing here” but really this being was created using a blueprint of zeros and ones zipping across space at the speed of light. A Cartesian ego or soul is not necessary for this claim to be true. We exist, with or without souls, but we don’t exist (in this world, as far as we know) without bodies. Neurons fire, thoughts are created, the functional units of a person move and act in all the right ways, but fundamentally OP and MB are not the same consciousness (perhaps there is a better word for this). If you snuff a candle and light it again, is it the same flame? By all the ways of counting it is, (the candle is physically the same, it follows the same rules of physics, etc.) except that there is something that feels wrong about not acknowledging the transition.
Another thought: knowing the outcome of BTT, I highly doubt that MB would undertake a journey back to Earth using this method.
Parfit offers four convincing arguments for solutions to his simple and Branch-Time teletransportation. They were convincing enough that by the end I found myself nodding along to his final point that my existence and life as I perceive it is simply a chain of psychological states and nothing more. But none of his theses, nor that conclusion, address the possibility that identity consists in body, as Gretchen Weirob argues. His argument rests on the premise that continuity of identity/existence, as we experience it, exists in psychological continuity and a “relation R” which somehow connects through a chain of psychological experiences.
In his thought experiment, Parfit decides to use simple teletransportation, in which his body is destroyed on Earth and made out of new matter on Mars, because his wife has done so many times and is okay. But what is his measure of “there is nothing wrong with her”(444)? Is it that she appears the same? Her mannerisms and outward behaviors indicate that she is the same person who identifies as his wife as she was before? The fact that she tells him she is his wife, can speak of past experiences, and says she remembers being his wife? Is it the fact that she looks the same as his wife did before simple teletransport?
Based on how he defines continuity through time, Parfit would most likely suggest that all of the above (aside from the looks) would qualify as reliable measures of what it means to exist as the “same” being through the teletransportation. We can believe that she is the same person if her external expressions of her internal psychological experience express no doubt of her “sameness” from before teletransport. What she thinks is only what matters.
But Gretchen Weirob in the Dialogue on Personal Identity invites the possibility that any apparent psychological continuity could be the result of false memories, a trick of the mind, or a delusion that exists in this new body is not an accurate representation of connectedness. That imposter has had those experiences implanted in his/her head , so that it seems that she comes from the same continuous experience as the original body. But what if her thoughts are akin to new thoughts just being born? Parfit asserts that continuity exists as a chain of psychological memories or states (like intention or desire) based on our internal experiences of who we are, and nothing more. However, I was still left wondering, despite all of the different definitions of personal identity offered, whether I would be comfortable calling a new body version of a friend who was teletransported “you” with the same meaning it had pre-transport. I don’t think I would trust that person like I did my pre-transport friend.
I disagree with both of Parfit’s solutions to his teletransportation scenarios, because I disagree with his definition of identity.
In the first, “simple” case (the one in which a person is scanned, destroyed, and virtually identically reconstructed elsewhere), I think that the product of the procedure is indeed the exact same person that originally entered the machine. This makes sense to me, because I choose to define a person as a psychologically capable human whose memories go back in time and are real; when I say “real,” I don’t necessarily mean that the memories are “true,” because whether they are in accordance with reality does not change the fact that they inform the person’s mind. Thus, in the simple case, the person who exits the machine is the same person who entered it, and the fact that this person’s original body was destroyed is irrelevant to the person’s identity, as long as the new body is an exact replica of the last. In this sense, I disagree that the new body’s identity is “indeterminate.”
Parfit’s “branch-line” case argument also makes little sense to me. He argues that, when the original person steps into the machine, he is duplicated and rebuilt elsewhere while maintaining his initial state as well (temporarily). Parfit believes that neither of these two new people are the original person, based on the rule that two identical beings cannot coexist. My response to this argument is that while the two new bodies are at least initially identical, the moment they started living their own, separate lives, they were different beings. And, furthermore, I believe that these two new people are BOTH identical to the original person, but that they are not identical to each other. In other words, their relationships are backwards with their original self, much in the same way that a normal, undisputed person’s identity is shaped by their former experiences as well as their current one. So, I think their can exist two new people who came from the same one in this case, and I don’t have a problem with this logic.
Incidentally, I think a good comparison is the case of identical twins. This is not terribly uncommon and it happens in real life, so it is a good example. Depending on when one defines the beginning of a person, it could be argued that at one point (a very, very early stage) two identical twins were the exact same “person.” Still, their divergent paths and experiences made it so that they were different people, undebatably. I don’t see how this is different from the branch-line case, but no one would dispute that two identical twins are indeed different people.
I found the Parfit selections interesting because it left me with almost exactly equal doubts and supports of animalism and psychological theory, but little faith in reductionist theory. In the simple teletransportation case, Parfit sold me on the idea that the Mars replica shared his original identity. If the chain of consciousness is continuous and each cell of the body is exactly the same, how could we argue that the replica and the original are not one in the same? This case contains elements of both theories, because psychological continuity is maintained, and it can be made animalist by connecting the idea that memory is dependent on neurological plasticity (so continuity is maintained by virtue of the fact that exact cellular structure is maintained).
Then Parfit introduces the branch-line teletransportation scenario, which seems to completely contradict every conclusion I had drawn from the previous situation. I think that even upon first reading, it is intuitively apparent that, if A goes in and B and C come out, A is gone and B and C are different individuals with ‘new’ identities. However, as Parfit points out, this indicates an attachment to a ‘further fact’ because both B and C are psychologically and physically continuous with A and therefore the same according to both animalism and psychological theory. Up until this point in the reading, Parfit had sold me on every idea he presented, but I found it difficult to buy the idea that the U in his equation “does not matter, or matters only a little (450).” I found myself more taken with the idea that our continued existence “must be all or nothing,” which he immediately and somewhat jarringly chases with “This is not true (451).” It seemed to me that his only argument to support this bold statement was based more on what he desired to be true than on logic or reason. Perhaps I’m oversimplifying, but he seemed to say that our continued existence can be found in the loose relationships between our current experiences and the future experiences of others and that he embraced this belief because it makes his death “seem less bad.”
Overall, I think the teletransportation scenarios raised some really interesting questions about the intersection of other identity theories, but Parfit’s follow up arguments for the strengths of reductionism did not resonate with me. For a view that seems to reject and even scorn the sentimentality of a Cartesian soul, Parfit’s theory seemed to rely quite heavily on emotional arguments rather than reason.
I believe that Derek Parfit does provide the correct solutions to his teletransportation thought experiments. The thought experiments provide us with a clear illustration of why it is problematic to attribute personal identity to an immaterial mental substance or ego. They also serve to show why Locke’s criterion of psychological continuity through memory is insufficient for describing personal identity. Above all, however, Parfit’s examples present the bizarre, but plausible, idea that personal identity may sometimes be indeterminate.
In his main-line thought experiment, it is very easy to say that the person on Mars is identical to the original person on Earth who gets into the teletransporter. Even with the belief in a Cartesian ego, it would make sense that the ego would follow the body and remain with it after it is teletransported. This becomes less apparent in the branch-line teletransportation thought experiment where the original person’s teletransportation results in the creation of an additional person rather than a replacement. In this case, which body would the Cartesian ego follow? It seems obvious that this ego, if it exists, would remain with the original body, rather than the teletransported one on Mars. And so, our original assumptions from the main-line thought experiment about the transferal of the Cartesian ego have been proven false.
It seems that admitting the existence of a Cartesian ego results in paradoxical situations. Therefore, it cannot exist, and our identity cannot be tied to it. This also means that identity can be indeterminate, especially in the case of the branch experiment where Bodies B and C are both continuous with Body A, but are not psychologically linked to each other. In these cases, we can see that the idea of “consciousness” is incompatible with and irrelevant to identity.
Does Parfit give the right solutions to his simple branch-line teletransportation thought experiments? Why/why not?
I believe that Parfit’s arguments are logical and so his solutions to the simple and the brain-like teletransportation experiments follow from his arguments. However, whether or not they are ‘right’ is more difficult to answer. I find that his logic is very convincing and I agree with his modifications of Locke that include broadening the psychological connection beyond memory and including overlapping chains of physical connections. The part that challenges some of my own internal beliefs is the branch-like teletransportation case. According to Parfit’s arguments, his conclusion in this case is that relation R, psychological continuity, is survival because this relation, and not personal identity, which requires uniqueness, is what is important. If you accept the argument that personal identity is not what matters, then his conclusion in this case is right. His argument therefore isn’t an ontological argument about what exists or what makes up these complex relations, but is instead about what is important.
I think that he dismisses uniqueness too easily. His claim is that it is an artifact of usage of the term personal identity and not as important as we think it is. Perhaps this is because our culture is a highly individualistic culture, which is reflected even in the government. That could be why this argument is unsettling. Personal identity and setting oneself apart from others is very important in our culture, which makes it hard to accept an argument where uniqueness is nonessential. Even if he is correct that uniqueness is a linguistic artifact that should not be central to psychological continuity and personal identity, the result of the terms being used in the way that they are is that for many people, including myself, it is very difficult to separate uniqueness and disregard it as a nonessential component. Therefore, my main objection is to the value thesis and Parfit’s claim that uniqueness, and thus personal identity, is not as important as psychological continuity. The consequence of this objection is that I believe that in the case of the branchlike teletransportation, his conclusion is incorrect and that this situation is not analogous to survival.
Does Parfit give the right solutions to his simple branch-line teletransportation thought experiments? Why/why not?
Parfit proposes a modern version of the idea of the self, modifying Locke’s view, in the selection from Reasons & Persons. Unlike Locke’s “direct connections”, Parfit’s theory allows for overlapping chains of psychological connections. He presents his theory with examples of theoretical simple and branch-line teletransportations. His argument concerning the identities of the original body and the copy made on Mars is supported with the idea of a different cause of one’s psychological continuity. The copied being still retains memories from before, even with a replicated body. In this case, psychological continuity is not necessarily a barrier to you not considering the “other” person as the “same” person. However, in Parfit’s branch-line example, neither the copy existing on Mars nor the “damaged” body produced after the teletransportation is, in Parfit’s eyes, identical to the original person. Due to the fact that both the body on Earth and the copy on Mars exist at the same time, albeit in different locations, the uniqueness condition is violated. Parfit believes that personal identity, as we use it, is transitive. In conclusion, he thinks that psychological continuity trumps personal identity.
Although Parfit presents a strong argument, his overarching concept of the inability to determine whether the copied body is the original person leaves the reader hanging. He is denying us the ability to numerically identify the idea of the self. This “grey area” does not provide us with concrete answers, but does account for varying degrees of continuity and connections.
Considering the entirety of Parfit’s argument, I agree that the idea of the self cannot be simply, numerically defined. However, I disagree with his dismissal of the concept of personal identity. I have trouble conceptualizing the idea that with the death of the “damaged” body (in Parfit’s branch-line teletransportation example), some aspect of psychological continuity lives on through the copied being on Mars. With different bodies in different environments, how can continuity exist? How is the idea that this other being is continuing his life as a “copy” of your being comforting in that you might still “live on” in some way or another? I believe that when the “damaged” body dies, the “copy” will no longer be able to be associated with another being. This body on Mars will follow its own path, even though there are similarities upon its origination. The link disappears when the “original” no longer lives on.
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
Although this may be the minority opinion, I found Derek Parfit’s explanations and conclusions very refreshing. Due to our human patterns of recognizing a person by their appearance, contextual setting and personality, it is hard to formulate a theory like Parfit’s on personal identity without considering objections. As Nathan touched on his his response below, I like how Parfit “tells it like it is.” Although he offered no definitive conclusion, his rhetorical concluding remarks were satisfying enough for me. Does it really matter if it is our same body or not? If another being is psychologically continuous with us then isn’t that good enough? In Parfit’s eyes, it is indeterminate whether Person A is Body B or whether Body A is exactly identical to Body B. The answer could be yes or the answer could be no. It doesn’t really matter and in some way I found this the most settling conclusion to these teletransportation experiments.
Due to the more direct psychological continuation of the simple teletransportation problem, I can see people would find this a more pleasing idea. Their psychological continuation would be much more present and although the body may change, the individual’s consciousness remains continuous and the same. However, in the branch line teletransportation, consciousness from one body to the next diverges. I think the process of letting go of our consciousness is the most unsettling event for humans to comprehend. This attachment to our psychological consciousness is why we have to work everyday to repress our fear of death. In thinking about Parfit’s stance, Animalism comes to mind. Supporters of this theory would argue that our minds and bodies are so connected that we can not exist anywhere else outside of our bodies. But for those that find objections to this can agree that there is something else outside of our physical brains that are allowing us to think the way we do. In light of our consciousness being somewhat separate from our bodies, then we can not fully object to the idea of our consciousness existing somewhere else.
As previous posts also mentioned, I feel that Relation R is very important to Parfit’s conclusions as well. Psychological continuity is desired by humans in their struggle to let go of their consciousness. The question that comes to mind is how can we really determine the uniqueness of our current consciousness from previous consciousness that may have embodied other people previously? If we can not be completely sure that our consciousness is unique to us as individuals or to our bodies, then how can we disprove the continuity of our consciousness elsewhere after we die? These are questions I don’t know if we will ever have the answer to. But for me, in terms of embracing my death one day, it is way more settling to know I will continue to exist at least psychologically somewhere else.
Parfit’s Selections from Reasons and Persons introduces the thought experiment of simple vs. branch-line teletransportation. As implied by the name, the simple teletransportation example reads in a relatively straightforward manner. Body A enters the transporter and the consciousness responsible for body A will awaken in an identical body on Mars. This become more complicated though when the question is introduced as to whether these two bodies are the same person. Parfit takes an interesting stance on this matter; claiming that they could be, yet they could not be, and ultimately that it doesn’t really matter if they are or not. The last segment of this argument, however, relies on one not believing in what he refers to as a “further fact” – which I took to be analogous to the soul. This is where I found myself starting to disagree with Parfit, in that I do fundamentally believe in a soul and thus, to me, the result of whether these two bodies do/do not encompass the same person or identity does matter. I also thought that Parfit seemed to contradict himself slightly later in the article when, while presenting the division analogy, he claims that “I would survive if my brain was successfully transplanted.” Although I may be misinterpreting his argument, it came off to me as if he was implicating the brain as the locus of an identity, or an “I”. If this were to be true, then it seems as if not only would the answer to his question matter, but that they wouldn’t be the same person as the original brain of Body A was destroyed during transportation (unless he believes that all that is required to perfectly replicate the brain is the recording of the exact state of all of its cells).
In comparison, his branch-line anecdote provides a more perplexing, yet ultimately resolvable (by his standards) problem. In this example, body A enters the teletransporter and is seemingly identical to both bodies B (on Mars) and C (on Earth post-teletransportation). However, Parfit is quick to distinguish these entities having the same bodies and subsequently being the same people/having the same identity. In the psychological criterion that he sets forth to support an extension of Locke’s argument, he states that psychological continuity can only be present if there does not exist a different person who is also psychologically continuous with the original person (claim 4 – the “uniqueness clause”). Branch-line teletransportation appears to directly violate such a clause, and thus implies that neither body B nor body C is the same person as body A. He also brings in the idea of exact similarity vs. numerical identity; in which he posits that, although body A may be qualitatively identical to bodies B and C (via the club/nation argument), that they are two different people, and thus not numerically identical since the life of one overlaps with the lives of the others. I agree wholeheartedly with Parfit here that neither B/C is identical to A, however for a different, more Cartesian, reason. The idea that one person can be occupying more than one place in space and/or time is something that I have always deemed, at its core, impossible – at least in the metaphysical universe that I believe us to exist in. In reality, this may be more of a difference in language and consequently more analogous to his “uniqueness problem” than I had originally thought. One thing that is for certain though – although I should hesitate to use such a word in a discussion like this – is that Parfit’s thought experiment got me thinking more deeply about the self and my identity than I had previously believed to be possible.
Parfit’s teleportation example calls attention to the modifications that he has made to Locke’s theory of personal identity. By deviating from Locke’s initial memory criterion, Parfit steps away from the notion that one’s continuous memory is what allows them to persist over time; instead, he focuses on a different psychological connectedness. By presenting his modifications in the form of the teleportation example, Parfit is able to demonstrate the effectiveness of his changes to Locke’s theory and also call attention to several complications. To this end, I believe that Parfit gives some correct solutions to the simple and branch-line thought experiments.
With respect to the simple thought experiment, I believe that Parfit’s solution is in line with his definition of personal identity. In defining personal identity, he puts an emphasis on allowing for overlap in psychological connections and broadening psychological connections to include continuity of belief, desires, and intentions. With these in mind, it seems to me that in the simple thought experiment the person exiting the machine on Mars would in fact be the same person as they were on Earth. This would be the case because, despite temporal discontinuity, the bodies would contain the same psychological connections, making them the same person. However, given Parfit’s value thesis and emphasis on the relationship between psychological continuity and uniqueness, it would seem that both bodies in the simple thought experiment contain different people. These two conclusions make Parfit’s declaration of indeterminacy correct. That being said, I think that his theory may contradict itself. At the very least, I have trouble understanding the logic behind the uniqueness. Why can’t a different person Z who is psychologically continuous with Y exist?
It is in this same vein that I question Parfit’s solution to the branch-line thought experiment. If people can have different psychologically continuous stages (X and Y) over time, why can’t branch-line teleportation be described as two different stages of the same people? Parfit suggests that body B and C, the result of teleportation are not the same people as person A. If you consider B and C different stages of person A, both psychologically continuous with A, but unique from each other, why can’t they be the same person? I would argue that this flaw in the argument prevents Parfit from solving the problem of transitivity. Furthermore, I think that the solution Parfit offers for the branch-line thought experiment is flawed.
I agree with Parfit’s logic in some of his modifications to Locke’s theory; however, I disagree with the way he applies them to solve the simple and branch-line teleportation thought experiments.
Although Parfit was in using his division of simple teletransportaiton and the branchline teletransportation to show how personal identity can be represented, I cannot find myself completely agreeing with either option. While I cannot necessarily point to one specific aspect of simple teletransportation that I find problematic, at the same time I cannot completely believe in it either. On the other hand, I know I find branchline teletranpsoration troublesome because it is not derived from the proper train of thought. Parfit admits that branchline TT does not yield two individuals that are identical; however, his explanation as to why this should not matter seems to be a cop-out answer. The value of an argument does not necessarily constitute accuracy. His reductionist proposition for understanding self-identity under the assumption that uniqueness is not important is not good support for saying why duplication is not a problem for determining personal identity. I would not agree that uniqueness is just a tenet that adds to the value of personal identity, but an essential component of what defines personal identity. His definition of personal identity confuses me because it is more emotionally based on his own preferences for how he chooses to view life rather than an argument for what is the right way.
Obviously there are several components to what creates one’s personal identity. However, unlike a burger, which will still be a burger without lettuce, the components of personal identity are all essential to the definition of personal identity. In branchline teletransporation, the two people that come out as bodies B and C are not identical to each other, however you can say that the initial person A came back out as body C (the person that ends up dying a few days late). This is because he/she has maintained the same body and mind as when he/she first entered the teletransporter. Therefore we can consider person A as having died after a few days while body B lived on in Mars. In that case, body B and body C need not be identical since person A= body C and body B is not equal to body C and therefore body B need not be identical to person A. When body B dies then, body C does not live on as person A. Parfit claims that body B and C are not identical but because of the value of considering them to be equal even though they are not unique, you can claim them to be the same person. He makes this claim because he would like to think that he lives on even after he dies, but this is not a strong enough reason to make uniqueness of factor of value rather than accuracy.
I’m actually not quite sure what I think about Parfit’s arguments. On one hand, the idea of reductionism makes perfect sense to me, in that I think it is reasonable to assert that there isn’t really any type of “Cartesian Ego” (that is, to say that personal identity is simply composed of impersonally describable facts). On the other, I find that I cannot easily accept many of his other conclusions, particularly the ones that have to do with the teletransportation scenarios. For instance, his ‘resolution’ of the simple teletransportation situation seems like the absolute worst answer that anyone could possibly give. Based on his story, it seems clear (at least to me) that the person walking out of the transporter on mars would be the same person that walked into it on earth. After all, psychological continuity and uniqueness both seem to be maintained, so it appears as though both parts of the PI equation remain fulfilled. But even if I’m wrong (or if I’m misreading his arguments), his answer still seems terrible. What we’re looking for in a theory of personal identity, I think, is confidence, and there is nothing here to inspire confidence. I suppose that the answer technically makes sense given his theory of reductionism (if personal identity is just a set of interrelated physical and mental events, it is kind of weird to ask whether two sets of events can be counted as the same), but it’s just so… bad! If I was offered the chance to get in a teleporter, the question “am I going to survive this?” would strike me as fairly important. And Parfit’s answer, as I understand it, would be some combination of “yes and no”, “maybe”, “I have no idea”, and “it doesn’t matter.” But it does matter! If I asked the question “will the person who walks out of this teleporter be me?”, answers like “persons are indeterminate” or “there is no correct answer” would be terrifying! Again, they technically make sense, but would anyone want to hear them before pressing their own big green button?
I object to Parfit’s branching path answer as well, although this reaction is a lot less ‘visceral’ than it was in the first scenario (probably because the conditions are much more complex). Essentially, I think it seems fairly obvious that the person who walks out of the teleporter on earth is the same person that walked in. After all, nothing actually happens to the narrator as he is standing in the transporter… he walks in, the machine makes a copy of him and sends it off somewhere, and then he walks out. At no point during the story (it seems to me) does the narrator ’die’ (or even black out), and yet suddenly Parfit asserts that he no longer exists (and instead has turned into 2 different people)? That makes no intuitive sense to me. If he walked in, remained conscious the whole time, and then walked out, when did this split happen? Does it have any practical implications for the person who remains on earth? What is the point of calling the person that walked out a ‘new person’ if he is mentally and spatially continuous with the ‘old person’?
Honestly, the most intuitive way I can think about this is in terms of who the narrator is. In the single path situation, the narrator is the same throughout the whole story, and this implies that the person remains the same throughout the story as well. In the branching path scenario, by contrast, narration sticks to the ‘earth-bound person,’ and this implies both that the person who ends up on mars isn’t the same as the original person and that the person who stays on earth is the original person (since he is the one narrating the whole time). Again, I could be picking this out just because it mirrors my own beliefs, but it does seem to me to be the clearest way of thinking about these situations.
These thought experiments are troubling, they are eerie, because they force us to consider and wrestle with the idea that who we are now may not be who we are in 20 minutes and isn’t the same person from three years ago and Parit expects us to follow with the “doesn’t really matter” conclusion. In the passage provided in our handout, the final sentence, “Ordinary survival is about as bad as being destroyed and having a Replica,” is repeated and italicized. To the average human, personal identity is a pretty important concept (flashback to teenage angst, ‘finding yourself’ in college). I like what Parfit did with these examples, he simplified personal identity by removing the expectation that weighs down the Cartesian inalterable ego and, in a sense, I agreed with him and felt freed by the end.
In a sense. If I went through a simple teleportation device and pop out on the other end, feeling and looking exactly as I did, that would probably be enough for me to discard any insecurity about whether or not I am me. ‘R’ continued. I feel like I’m me. Great, let’s get a snack. With branch-line, however, I don’t think I (we?) would be quite so relaxed. First of all, I don’t think that you can argue with the claim that AnnieA ceased to exist the moment the machine didn’t dissolve her. AnnieB left the machine with a completely different consciousness than AnnieA, and AnnieC on mars will do the same as soon as she finds out AnnieA’s body remains on Earth. Knowing of each others existence breaks the continuity of consciousness between AnnieB and AnnieC with AnnieA. That break in consciousness, that ‘R,’ matters, and I don’t think that any of the possible Annies would be able to brush it off and get a snack. ALTHOUGH, if AnnieC never found out about AnnieB living past the machine, she would keep ‘R’ intact, and AnnieB may be able to think that her own demise doesn’t matter, so long as her unaltered consciousness continues elsewhere.
Derek Parfit’s presentation of the simple teletransportation and branch line teletransportation seemed relatively simple when I first read them. Then I thought about them a little bit more, and everything seemed a little less clear… First I will address Parfit’s answer to the branch line teletransportation model. Parfit says that body’s A, B and C in this example are not numerically identical, but they are qualitatively identically. I agree in thinking that neither A, B, or C are identical persons but that does not mean that they are not exactly similar beings. It is something like cloning. If I were to clone myself (which is essentially what is happening in this branch line example) I would still consider myself the original, and the others identical copies of myself. I do admit that the branch line model is different form cloning in the way that after (or in the instant) the teletransportation occurs, the two people start different trains of consciousness. This would mean that they are not identical, and further more, I would hesitate to say that they are even exactly similar. The second that they start adapting and reacting to stimulus of their environments in different ways, they are no longer exactly similar. With this said I bring up another thought. If person A (on earth) dies soon, in my opinion, there would not be a huge loss. There will still be a continuous memory and consciousness that exists, in the form of person C on the moon. Assuming person C can safely get back to earth and resume his normal life, all would be well. All I have just stated is in assumption that there is no soul essential to comprise a person, in addition to the obvious physical matter of the body. When the soul is brought into the discussion is where I start to doubt Parfit’s views.
In response to the simple case of teletransportation, Parfit says that it is ultimately indeterminate whether body B (the body on mars) is person A (the original person from earth). He says that we could either say that it is or is not, it is virtually the same thing. We know the facts about the situation, and it doesn’t fundamentally matter if we call an exactly similar person the same person. Parfit’s use of the example of a chess club at Middlebury was very clear and to the point. It is a good analogy to his solution to the simple teletransportation. He claims that if one is holding on to the desire to get a yes or no answer, they would be holding on to the idea of a soul. The idea of a soul brings up an interesting thought for me. At first glace I think I agree with what Parfit says, in that it doesn’t matter what we call body B, because we know the important facts surrounding it. It gets more complicated for me when I start thinking about the existence of a soul. Having a soul or some other immaterial consciousness guiding us would be an argument against indeterminism, because this consciousness would not be with the new body on mars. Or at least we cannot prove that it will be. I personally think that a soul may exist, but I am not positive how it intertwines with the matter that makes up a human.
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
The simple teletransportation thought experiment is, indeed, simple and not particularly difficult to grapple with. Does the same person come out as went in? Is Body A at T2 the same person as Body A at T1? Parfit says yes, no, and it doesn’t matter. I agree with him a pro pos the club analogy. I always find myself understanding and enjoying philosophers who “call it like it is”. I believe there is sometimes as much soundness to an argument that posits, “Well, we can all understand that, and see the facts, and so it doesn’t really matter”, as there is to one that follows the rules of formal logic. If every single cell of my body is disintegrated and then decoded and reconstructed, in such a way that my consciousness is exactly preserved despite a momentary blip, who can argue that the duplicate is not the same as me? Further, who can argue that the duplicate is the same as me? I say, any man, and all at once, and that is satisfactory for me.
In the branch-line thought experiment I am also mostly persuaded. Body A is the same person as Body B (by an extension of the simple case), and Body A is also the same as Body C (also by an extension of the simple case), but who could possibly argue that Body B is the same as Body C? Who could argue that two things that exist independently of one another and simultaneously occupy different parts of space are the same thing? The very idea goes against our entire system of logic down to the most fundamental axioms of mathematical set theory. So what, then, does happen? Well, Parfit says it doesn’t matter and we shouldn’t care. The fact that we are irked by this scenario is a remnant of some ill-informed and unconscious desire for a Cartesian ego which, as Parfit posits, simply doesn’t make sense. What matters in determining “personhood” is psychological continuity. So if A is pcontinuous with B and A is also pcontinuous with C, that should be enough to explain who is who. Each is A, but neither is the other. The only obstacle to grappling with this is spiritual.
What would happen, now, if B and C met each other face to face, person to person? I’ll leave that to science fiction.
February 28, 2014 at 8:27 am
Parfit does give the right solutions to both his branchline teletransportation thought experiment but I have a more difficult time reconciling his response to the simple teletransportation thought experiment. Parfit seems to think that there is a justification for two responses to this experiment — one response saying that the person waking up on Mars is the same as the one that was on Earth and one response says that they are two different people. To me, Parfit’s psychological criterion of personal identity is met if you assert that the person who wakes up on Mars is the same as the one who left earth. Although objectively we may find that there is a gap in this person’s psychological continuity, to the person in question there would be no gap and it would feel only like a moment. Therefore, in the case of simple teletransportation, when the subject wakes up on Mars they would fit all three primary tenets of the psychological criterion and be the same person that they were before the teletransportation.
Parfit’s solution is correct in the case of the branchline teletransportation. His solution is both logically and intuitively correct; although it is posited as fitting the psychological criterion there are some aspects of his solution that seem to be in agreement with Olsen’s animalism theory that the human person is numerically identical to the human man; once the human man ceases to exist even if there is a human man exactly similar (like the person on Mars) the original human person would cease to exist. Parfit’s solution is also correct because the moment that each individual was created in their separate locations, they would begin to sense and perceive the world differently from each other. Once there was one human on Mars and another identical human on Earth, the two would cease having psychological continuity and cease continuity in the way they process sensations. What is seen on Mars would not be seen on Earth and vice versa. Parfit’s solutions for the branchline solution seems more intuitively correct whereas his solution for the simple teletransportation answer seems less so because of the idea of there being more than one correct answer.
February 28, 2014 at 12:27 am
Parfit’s views on personal identity are rather interesting. After reading Locke, Parfit’s modifications seemed to me to have corrected what appeared to be a somewhat flawed view. What I had trouble with accepting, was the idea that memory was primarily what informed one’s personal identity, since memory seems to be almost a necessary precondition of one’s personal identity. Parfit’s explanation of the ‘self’ is instead more appealing- it talks about the idea of ‘psychological continuity’ through time as constituting personal identity. He differs by saying that this conception of the ‘self’, of personal identity, is informed by a combination of psychological elements- opinions, external interactions and experience, intentions, as well as memories. This opinion seems a pretty rational way of looking at personal identity, so, for now, I would have to say that I agree with Parfit.
Parfit’s examples of the teletransporter, however, required me to ponder this assertion further. In both the simple and the branch line teletransportation cases, an issue that arose for me was the question of the transported person (Body B) being the same person as the original individual (Person A), i.e. having the same personal identity. Since there are two separate bodies, it is hard to say that both are the same ‘person’. Also, since the two are identical and have the same memories, beliefs, etc. at the time of transportation, it is also hard to assert that one of them is the original ‘Person A’. My conclusion was that neither of the two are the same as the original ‘Person A’. My reasoning was that since I could rule out the other two possibilities, what made the two bodies different from ‘Person A’ was the passage of time. As soon as the transportation occurs, the bodies are different because cells have changed, some have died, been replaced, etc. Also, with the passage of time, can come change in beliefs, intentions, etc. Therefore, unless we look at the state of the bodies and their psychological states instantaneously upon transportation, the fact that two separate ones exist, and are affected by time in different ways henceforth, neither can be Person A.
I think, when it comes to survival and our attitude towards death, this conclusion would make me disagree with the idea that we should regard this teletransportation scenario as the same as survival. Since the original ‘Person A’ body is destroyed immediately, besides that one instant upon transportation, the same ‘Person A’ survives no longer, and his trajectory of life henceforth will not be the same as if the original Person A had continued unaltered. However, I do agree with Parfit on the point that at the end, it really doesn’t matter whether A and B are the same as far as personal identity goes, or that I believe that it does not imply survival of the same ‘person’. Our memories and experiences and beliefs and everything of the sort will change inevitably over time, and so, in death, at the end, maintaining that idea of the same ‘person’ really shouldn’t make a difference.
February 27, 2014 at 11:48 pm
I find Parfit´s Branch Line TT solution creative yet too simple. Though I am not very religious, I still believe that personal identity is somewhat related to the Cartesian idea of a soul, and for Parfit to dismiss this completely in his experiments seems to be an oversimplification.
If an identical copy of me was to be transported through some type of machine all the way to Mars by the click of a green button, with another copy still on earth, I think there would be some loss occurred by my original self. Parfit argues that the body B now present on Mars and body C now present on Earth, though identical, would lead different lives once they felt their first sensation. It seems to me, however, there is a loss of continuous identity. Being a person, and person hood is continuous, from the moment you are born to the moment you die. By creating two separate people, none of them would in fact be original to A by the time that they die.
Though Parfit refutes this argument by saying that personal identity is irrelevant, I have to disagree. It seems he uses a mathematical approach to something that is far from mathematical.
February 27, 2014 at 10:19 pm
When I read Parfit, Wittgenstein just popped into my head. I don’t know if Parfit took influence from Witt, but their language and method are weirdly similar. “Criterion” has been a core idea of Wittgenstein. But here I want to talk more about Wittgenstein’s critic on philosophy itself, an approach I believe is also visible in Parfit’s thinking.
The strategy Parfit deploys is basically to dismiss questions like “Are A and B the same person?” as unimportant and valueless and thereby shift our focus to something else. Specifically he wants to downplay the idea of personal identity and highlight the notion of psychological continuity. If Wittgenstein were to comment on Parfit’s method, he would probably agree with it, but push Parfit’s idea further and say that the question of PI is an illegitimate philosophical question whose illegitimacy needs to be clarified by philosophy.
In what way can the question of PI be an illegitimate question? Parfit goes along the way to say that what matters is the fact, and after all the objective facts are clear, the question of PI – as I would further interpret it – is only a matter of how we translate the facts into subjective concepts we feel comfortable with, such as the very concept of personal identity. I believe for Parfit personal identity is less a factual question than a VALUE question, which is not of matter of truth but that of choice.
Buddhism has similar claim that personal identity or the notion of a self is nothing but an illusion. What’s more, it’s one of the many concepts coined by human beings that brings only confusion and ignorance. To achieve enlightenment one has to get rid of the notion of self. So I believe Parfit is not alone to argue that concept of PI should not be that important to us thinking beings.
February 27, 2014 at 10:03 pm
Does Parfit give the right solutions to his simple and branch-line teletransportation thought experiments?
In his teletransportation thought experiment, Parfit suggests that if reductionism is true (that is, there is no “Cartesian ego”), then it follows that persons are indeterminate. So the answers to the question “Is replica on Mars the same person as the body that went into the teletransporter on Earth?” can be yes or no, and it doesn’t actually matter. I found his solution rather unsettling because his theory indeterminacy of personal identity only holds true if reductionism is indeed true. However, whether there is “Cartesian ego” remains unresolved. Does personal identity merely consist in nothing more than certain impersonally describable facts? Are we nothing more than a brain, a body, and a set of interrelated physical and mental events? I doubt.
I may be digressing a bit, but I believe that how a person actually comes into being in both the spatial and temporal sense is highly relevant when we think about his/her personal identity. Let’s consider the following analogy: suppose I make a replica of Leonardo da Vinci’s Mona Lisa out of an advanced photocopier so that the “original” masterpiece and the replica are exactly and qualitatively identical. Can I then say that the two paintings are the same? They are identical in many ways, but I cannot seem to convince myself that those two paintings are fundamentally identical. One of them is a masterpiece painted by the world’s most famous artist while another is a qualitatively identical replica produced out of a photocopier. One is a work of creation and another is a result of replication. Their history – or the way they came into being – are in no way the same. Therefore, I would not conclude that those paintings are the same.
Should we care if the qualitatively identical paintings are the same? Does it matter? I guess it does; otherwise Mona Lisa would have an estimated value much lower than the current $760 million. Likewise, I believe it matters whether body A on earth is the same as body A on Mars. Perhaps we should go back to his theory reductionism and question its validity. To deny there is no soul or anything of that sort is a hasty conclusion. To say it doesn’t matter is nothing but an easy way out.
February 27, 2014 at 10:00 pm
I find flaws in both teletransportation cases posed by Parfit. In the simple teletransportation situation, in which the original body of person A is destroyed and his brain states are replicated into a new body (which occupies a different time and space) called Body A, it is expected that this new body is person A’s. That is, the brain state composition is replicated in its entirety and the person on Mars is numerically identical to the body that WAS on Earth – and this I think, is a key part of the argument: since the original body was destroyed, there is no choice but to believe that the new body that A’s brain states now occupy (Body A) is the same person as A. After all, if one body is destroyed and another created, the “number” of possible A-persons remains one. There is no overlap in the lives of original A and his Replica. The branch-line teletransportation situation introduces the problem of duplication and a violation of Parfit’s own “uniqueness clause.” This conflict occurs because in this scheme, a “blueprint” of the body is taken and preserved in Body B on Mars, while the original body is maintained but apparently defected, referred to as Body C. Now Parfit is quick to say that Body B and Body C are not the same person as A, and if one were, it would violate the condition of uniqueness that is assumed. Now the “number” of possible A-persons is two, and how can one person be two people? Plus there is overlap between the original A and its so-called Replica Body B – but this raises problems like, “Who is Body C?” and “If they overlap, are they different people or merely the same person with strong psychological connectedness?”
To believe that the Replica after simple teletransportation is the same as his original would be to assume that the process, though decidedly destroying the original body, successfully replicated a numerically identical A on Mars to the A on Earth. But when faced with branch-line teletransportation and the problems of personal identity it poses, it’s tough to say – if teletransportation worked and created a successful replicate in the first situation, it should be able to create a successful replicate in the second. So then Body B would be A, and Body C would be… no one? If you reject that simple teletransportation would produce a Replica that is actually A, you would thus reject that branch-line teletransportation could perform such a feat – perhaps the original person is destroyed, and no one is A now. But can Parfit’s teletransportation thought experiments be rejected due to just the duplication problem, or further because personal identity is more than just the arrangement of bodily cells and brain states?
February 27, 2014 at 9:55 pm
While I do think that Parfit’s perspective helped bolster Locke’s original argument on personal identity, it appears that there is a great dissonance between his thought experiments and his explanations behind them. Parfit questions Locke’s view on the dependence of the recollection of old memories on a person’s existence, and rather posits that there only needs to exist a continuous chain of memories between person X and person Y to be them to be the same. Moreover, Parfit’s takes into consideration other psychological connections in the event that memories cannot be preserved, such as beliefs, intentions, and goals. This notion of psychological continuity was a nice addition to explain cases where memories cannot be recalled due to physiological impairments.
I also agree with Parfit regarding the indeterminacy of personal identity, as exhibited in the teletransportation thought experiments. I found it paradoxical but quite effective for Parfit to present the teletransportation thought experiments as potentially exemplifying the “uniqueness condition,” while simultaneously disproving the condition all together. I can posit that the person on Earth and the person on Mars are in fact the same, provided that both persons become incapable of receiving new stimuli or suddenly die before gaining consciousness following teletransporation. There should indeed be a moment during which divergence has not occurred, thus making the ephemeral existence of person Z as psychologically continuous with Y possible. I also also argue that one’s social and physical environment is integral in shaping one’s personhood, and since no two persons can be at the same place at the same time, the same psychological continuity should not be possible among two persons. Parfit successfully showed with this experiment how indeterminate personal identity can be.
February 27, 2014 at 9:31 pm
Does Parfit give the right solutions to his simple & branch-line teletransportation thought experiments? Why/why not?
For the branch-line teletransportation, I too don’t understand why body A and body C (that one that stayed on Earth) are two different persons. Nothing happens to body A, except for an exact replica of it is sent to Mars. This is no different than like mentioned, getting an MRI, going through an airplane security scanner, taking a shower? I think I might be misunderstanding the “uniqueness condition.” Parfit is saying that the branch-line violates the uniqueness condition. Wouldn’t it not be violating it because body C is basically body A, and body B is not psychologically continuous with body A?
And in the simple teletransportation thought experiment, I am caught up with frustration. Parfit’s response is that it is indeterminate whether body B is person A, and why should it matter? But is the physical matter the same that makes up the new body B? Or was that matter destroyed and body B is made out of new matter. Because if that is the case, I wouldn’t think that they are the same, but then again I guess it doesn’t matter! I keep going back to what Andrew said in class about how given the opportunity, he wouldn’t go through with this simple teletransportation, and I feel the same. So I guess my real issue is that I am holding on to the idea of a soul, and then I ask myself why? Why do I feel so connected to my body? If reductionism IS true, then I think the value thesis makes sense. But the fact that I wouldn’t go through with this teletransportation makes me feel that reductionism can’t be true.
February 27, 2014 at 9:11 pm
While I agree with many of Parfit’s points, especially his ideas about psychological continuity, I find myself somewhat at odds with his interpretation of simple teletransportation and completely against his ideas about branchline teletransportation. I will begin with simple teletransportation. Here, Parfit says that it is indeterminate whether the body that emerges on Mars is the person who entered the transporter on earth. Initially, I felt strongly that the body on Mars must be the same person because the narrator of the story experiences a fluid transition. That is, person A was writing the story on Earth and when he woke up an hour later on Mars, the narrator was the same and continued his story. After further thought however, I realized that by nature of the inherent psychological continuity, it could be a new and exactly similar person on Mars. This person would remember writing the story as if he were the author, and would thus continue writing as if nothing had changed. Where I disagree with Parfit is that even though it is indeterminate whether body A is person A, I think this is very important while he thinks it does not matter. Parfit wants to say via reductionism and the value thesis that it is irrelevant whether you or someone exactly like you emerges on Mars, but I disagree. I am fully aware of myself as a thinking entity, and if it is merely a perfect copy of me who emerges on Mars, then I would cease to exist upon using the transporter. There would of course be a perfect clone of me who emerged on Mars, and the rest of the world would not know the difference, but I would be gone.
I have several problems with Parfit’s interpretation of the branchline case. He says that neither body B nor body C is the same person who entered the transporter. I disagree with this interpretation. In terms of the uniqueness condtion, what Parfit reasons seems to make sense. However, when you think about the details of what his interpretation implies, it begins to seem ludicrous. In the branchline example, you would walk into the machine and it would scan you but leave you intact. Based on what Parfit says, the second this machine turns on, you are somehow no longer you. This does not make any sense to me. If someone takes my photograph and says they can use it to make a perfect, psychologically continuous, clone of me, taking my photo does not suddenly mean I’m no longer me. I know that I am still the same thinking entity, and nothing has changed. Thus, the body that walks out of the machine on earth is the same person who entered, and the body on Mars is merely a perfect clone. It follows that the value thesis, where having a heart attack while your clone lives on is about as good as survival, seems silly to me. If you have a heart attack and die, the thinking entity that you are is still very much dead no matter how many identical clones you have living on Mars. Thus, having a clone live on instead of you is very different from survival, even if the rest of the world can’t tell the difference.
February 27, 2014 at 9:00 pm
In answering the above question, it is important to note the distinction between giving the right solution–that is, the logically sound solution–to Parfit’s experiments given his assumptions and giving the solution that we want believe is the case. Parfit’s reasoning works in a framework that is supported by several premises and definitions, including the definition of psychological connectedness and continuity (which he defines, arbitrarily, as over 50% connectedness), the psychological criterion of existence, and relation R. He also assumes that there is not a Cartesian ego, among other assumptions. These premises and definitions could be debated, but that will not be the purpose of this post. Instead, this post will argue that Parfit is correct in his solutions to the simple teletransportation (STT) and branch-line teletransportation (BTT) examples within his logical framework.
Given all of his definitions, it is indisputable that after STT the facts do not lead to the logical conclusion that the person on Mars must be either numerically identical or qualitatively identical to the person who was destroyed on earth. Rather, the facts leave open the possibility of both. The facts are that the person on Mars will be physically exactly similar to the person on earth and will be fully psychologically continuous with the person on Earth. As Parfit says, the replica on Mars could “be me” or it could be “someone else who is exactly like me” (447). There is no way to determine which one of these is the case. Parfit argues that in order for these hypotheses to compete, we must accept some further qualification of existence, something like the Cartesian ego,or a mental, non-extended substance. Parfit’s reasoning seems to be perfectly sound, and I would agree with him here, even though the result seems non-intuitive.
As for the BTT case, I think Parfit is also right, given his premises and definitions. Parfit’s claim is that the two people–the one on Mars and the one on Earth–are qualitatively, but not numerically identical. This makes sense since they are both physically qualitatively identical, and both have relation R to the original on Earth. Since neither is unique, however, personal identity is not preserved since PI = R + U. But, according to Parfit, that is not what matters, so this case of division should be regarded as “about as good as ordinary survival” (449). Although double survival is not the same as ordinary survival, it is not the same as death. I would have to agree with Parfit here, once again, even though the result might seem a bit unsettling.
I would like to respond respectfully to the point that Evan Gallagher made in his post that “[w]hat we’re looking for in a theory of personal identity, I think, is confidence, and there is nothing here to inspire confidence.” I think that everybody is entitled to their own view of personal identity, based on what they want to get out of that definition. For me, however, this discussion of personal identity is not about inspiring confidence, it is about discovering the truth about personal identity. If it turns out that Parfit is right, and that there is no determinate way to say whether or not we exist after teletransportation, can we dismiss this conclusion on the basis that we don’t like it since it doesn’t inspire confidence? I think that it is is misadvised to go about searching for a theory that will fit a particular need. To do so would be to confuse the positive with the normative. As Gretchen Weirob argues in the Miller dialogue, there is some unalterable, true fact about the matter, and our societal conventions about the personal identity do not change its true nature.
February 27, 2014 at 8:57 pm
Parfit states that if reductionism is true, it follows that persons are indeterminate in the question “Is person X the same as person Y?” does not have an unique correct answer- it can sometimes be correctly answered in either way. In the case of the simple teletransportation example, Parfit suggests that Body B is not necessarily the same as person A. I find this problematic in that there are many actual cases similar to simple transportation such as sleep or being in a coma. Would Parfit say that we are not the same persons when we awake from sleep as when we went to sleep?
In the branchline example, I believe that the person follows the consciousness. I think it is significant that when he awoke, his conscious remained with Body C. Therefore he remained consciously continuous with person A. But then what happened to Body B? Well, I agree with Parfit when he says, who really cares? Both Body C and B may be consciously continuous with person A, but this does not mean that they are consciously continuous with each other. So, if the consciousness splits in two, where does the person go? Although it may seem like the easy answer, but I agree that, because the person had to choose between two bodies, it is indeterminate.
Even though the question of “Is person X the same as person Y” indeterminate in the branchline example, I think that Body B is person A in the simple teletransportation example. This is because, in the simple example, the person remains in one body and does not face the problem of being in two places at once. Rather than having to choose between two bodies, the person definitively transfers to one body, which does not violate the duplication law.
February 27, 2014 at 8:56 pm
Parfit successfully modifies Locke’s psychological argument by (a) allowing for overlapping chains of psychological connection/continuity of experience, and (b) broadening “psychological connections” to include beliefs, desires, intentions, goals, hopes, etc, in addition to memory. In this way, he fixes the amnesia, transitivity, and duplication problems.
In response to the simple teletransportation thought experiment, Parfit essentially says it doesn’t matter whether person A (on Earth) is the same as person B (on Mars), and if you are wanting to give a yes or no answer to whether they are the same or not, you believe in a soul or “Cartesian ego”. In the branch-line scenario, he says neither B nor C is the same as person A, and that B and C are qualitatively, but not numerically, identical. I agree that B and C are not the same person—although they originate from the same person A, they form new experiences independent of one another, making them different people (except for maybe the split second when B and C are both created and haven’t formed separate experiences yet). Parfit says B and C are not the same because this would violate the uniqueness clause. Perhaps I’m misinterpreting this part of Parfit’s argument, but this seems contradictory given that he later states that uniqueness doesn’t matter. Setting that aside, after thinking about Parfit’s overall view, I agree with him.
At first, I found it hard to let go of the uniqueness (U) component, which Parfit deems irrelevant, in his equation PI = R + U. At first glance, uniqueness seems to be so central to what we call personal identity—how could Parfit deem it so unimportant? However, once I thought in terms of Parfit’s reductionist side, I let go of this idea and actually felt relieved, and even comforted by his theory. The “my division” example makes sense to me—there is psychological continuity between A and B, and A and C, and this is all that should matter. PI should depend only on my own psychological continuity (intrinsic), and not the extrinsic relation of uniqueness—just R is enough. It feels strange to set aside the idea of the soul, but it restores my comfort knowing that I will live on through psychological continuity in some other body after I die.
February 27, 2014 at 8:55 pm
I believe that Parfit gives the right solutions to both thought experiments based on his view of personal identity. He gave the equation of personal identity as PI= R + U with U representing uniqueness and R representing the relation of psychological continuity. According to this equation, it is indeterminate whether the body (A) that enters the portal is the same as the body (B) that exits the portal in the simple thought experiment. We know that R is constant from body A to body B because the consciousness of the person who entered the portal is completely copied and transferred. Can we say that the person is still unique though? One could argue yes because the body is a complete replica or one could argue no becuase even though a replica was made, the original body was destroyed. We also see a correct solution based on his perspective of personal identity for the branch line thought experiment. Although his solutions do match his criterion for personal identity, I don’t agree with Parfit’s solution to the experiment. He presents personal identity as a combination of continued consciousness and a form of animalism. I believe uniqueness is not needed to define personal identity. I believe the relation of psychological continuity is all that is needed. I find more agreement with his value thesis. Uniqueness does not matter. What matters is the continuation of one’s thoughts, beliefs, morals, emotions, etc. Where Parfit and I differ is that I believe that this continuation of consciousness is all that is needed to define personal identity while Parfit believes that uniqueness still plays some role in defining PI.
February 27, 2014 at 8:52 pm
I think Parfit does give the correct solution to his simple and branch-line teletransportation thought experiments. However, I still find it pretty difficult to say I would press the green button and send a copy of myself to Mars. There is something inherently distasteful about this idea to a human being—the thing that wakes up will not be me, despite the fact that it looks, walks, talks, acts, and thinks exactly like me. And, because I do not believe in a Cartesian soul, Parfit is right to say that there is an intrinsic contradiction between my professed beliefs and actual actions/desires. Parfit uses his teletransportation thought experiments to prove that personal identity (specifically uniqueness) does not really matter—if the relation R (psychological continuity, continuity of experience) defines most of personal identity, the fact of survival is clear in both thought experiments. So, even when his uncopied body expires and his identity dies, he concludes that in a small way his experiences continue through affecting how alive people think. While this view has apparently liberated him from his fear of death, I can’t say I’ve gained this same benefit.
I am still slightly confused about one aspect of Parfit’s conclusions. Considering the branch-line case, let’s call the original person on earth person a, the person that steps out of the machine on Mars person b, and the damaged original person c. It is clear that person c is the same as person a—they are psychologically and physically perfectly continuous. Parfit makes it similarly clear that person b is the same as person a, and I accept this part of his argument. However, I wonder if Parfit would claim that person b is the same as person c. Persons b and c are strongly directly connected to person a, which defines a link in Parfit’s overlapping memory chain—but at what point do they become different people?
February 27, 2014 at 8:50 pm
Parfit’s teletransportation story poses some very interesting and convoluted problems for conceptions of personal identity. Although it seems more complex at first, the branch-line case, involving a copy of the narrator, is perhaps the better place to begin examining Parfit’s arguments.
In this situation, an exact copy is made of the narrator, who remains alive, whole, and conscious on earth. According to Parfit, a personal identity requires both psychological continuity (going from his own definition, a modification of Locke’s) and uniqueness. In light of this, it seems that he would say that Person A ceases to be the instant that body B is created and C walks out of the teletransporter. Given the rationale that the two bodies are indistinguishable and have all the same memories, it doesn’t make sense to say that only one of them is person A, and both of them obviously can’t be. We are forced then to concede the rather strange third option that neither of them is person A. I am willing to accept this with a few constraints, which I will talk about later, but I am still left with the question of, when body C succumbs to a heart attack, does body B then become person A, or do they remain their own separate person? In essence this is the same question that is posed by the simple teletransporter case. In both, whether hours later or days, the original body that stepped into the machine is destroyed, and there is a single body left on mars.
In the end, one’s interpretation of this result relies on their beliefs about the metaphysical nature of the world. I myself follow the animalist school of thought. Therefore, it is inconceivable that the body on mars truly is the identical person that stepped into the machine and pressed the green button, since the person and the body are one and the same. Nevertheless, a person is left who believes, and whom society believes, to be the same person. In the grand scheme of things, in the absence of an enduring soul, all the remains of a person is the influence that they had on others and the world around them. Therefore, I find myself in agreement with Parfit that it doesn’t really make a difference whether the new body is you. If it is, all the better; if it isn’t, you’re gone for good so you won’t care, but the net effect on the universe will be the same as if it were.
February 27, 2014 at 8:44 pm
At this point I’m definitely not ready to reject either of the conclusions that Parfit draws from his thought experiments. That being said, I am a little wary to accept both of his solutions wholeheartedly because I think that there are some inconsistencies in his argument. He starts off very carefully defining personal identity, psychological continuity, and psychological connectedness. I was happy reading this part because introducing/ redefining these terms patched up some major holes in Locke’s argument. After reading the simple teletransportation scenario I was quite convinced that the person who came out of the machine on Mars would essentially be the same person as the one who entered the machine on Earth. With the transitivity problem solved, I couldn’t think of anything important that the person on Mars would have that the original person hadn’t.
Like most people, I was a little more uneasy when Parfit proposed the Branch-line teletransportation scenario. But having already accepted the continuity between the two men in the simple scenario, I couldn’t think of how to refute the idea that the branch-line original would survive as two. If one person survived in the first scenario, then why shouldn’t two in the second? Psychological continuity seems to be something that is so personal; I cannot imagine how it could be compromised by the existence of a clone millions of miles away. Even so, it is hard to accept the “deeply impossible” notion that a stream of conscious could be split into two.
Although I can logically accept most of Parfit’s argument I was confused and a little troubled by how he ended by explaining away the importance of “uniqueness” to personal identity. When I read over the first part of the article again I was struck by how carefully (and sometimes arbitrarily) Parfit defined psychological continuity and personal identity in order to make sure he could take care of the transitivity problem. To me, it seems strange that he patched up that hole so neatly and then kind of danced around the uniqueness problem. As a philosopher, I think Parfit should be allowed to define personal identity any way he wants, but I am distrustful of the inconsistency with which Parfit treats these two problems. Intuitively, both problems seem to be equally substantial threats to Locke’s theory of personal identity. I guess I’d say that, like most philosophers, Parfit’s argument is sound based on the criteria that he has set for it, but I don’t think that it offers a perfect, or even a completely satisfying, interpretation of personal identity.
February 27, 2014 at 8:44 pm
Parfit’s simple teletransportation thought experiment initially resonated with me, and I was very inclined to say that the individual on Mars and the individual who pressed the button on Earth would be one and the same. However, his branch-line teletransportation argument quickly made me realize how problematic this view was. I believe Parfit has hit upon something essential and important with his concept of psychological continuity, which is both intuitive like Locke’s theory, and stands up much better against critiques such as amnesia, vegetative states, and even simple sleep. I believe Parfit’s psychological continuity truly is an essential part of identity, and he correctly applies this theory to both situations. I believe he is absolutely correct in his statement that being qualitatively identical is not equivalent to having the same personal identity.
However, I am not completely inclined to agree with his entire equation of personal identity: PI = R + U. Specifically, I would like to challenge his inclusion of uniqueness (U). While I cannot think of a good counterexample to specifically refute U, it leads Parfit to conclusions I am not comfortable with. Because he concludes that neither person/body produced in the branch-line scenario (B and C) is identical to the original person (A), the death of B or C is essentially a nonissue, as the survival of the other is “about as good as ordinary survival.”
Imagine the branch-line scenario occurring exactly as Parfit has described. The individual on Earth (let’s call him C) is told he will die in the next few days of heart failure. Now, imagine a doctor comes rushing into the room and says, “We’ve just revolutionized a new procedure that will fix the heart malformations caused by the teletransporter! We can save you!” Should C accept the procedure? Parfit claims that C’s survival is largely irrelevant. Yet, it seems obvious that C should leap at the chance to have this procedure performed, as it will extend his life another 40+ years when before he was certain to die within the next few days. Thus, I am not convinced by Parfit’s conclusions.
I propose replacing U in Parfit’s equation with M, where M is matter continuity. Matter continuity is similar to psychological continuity in that M = “there are strong overlapping chains of strong material connectedness between X and Y,” thus allowing for the slow recycling of matter within in an individual without claiming a new person has been created.
Now, instead of claiming that the simple scenario results in an indeterminant result, we may comfortably claim that the individual on Mars is a new person (explaining many people’s intuitive qualms about pressing that button), while C on Earth is the same person because he has both psychological and material continuity (R + M). C’s death would essentially be a sacrifice of his own life to create a new person, which he may not be enthused about. If we can save him, we should, because B’s survival is not as good as his own survival. This is in line with my hypothetical “doctor scenario” – he should accept treatment.
February 27, 2014 at 8:43 pm
Parfit’s thought experiments raise the question of self identity in an uncomfortable and initially far-fetched scenario. In the simple teleportation scenario, personB comes into being on Mars after being physically destroyed on Earth. If we let go of the idea of the cartesian immaterial mind, then Parfit’s logic and solutions make sense. If I lose consciousness and wake up on Mars with the same body and the same memories and thoughts–I must be the same person. Even if I have not come into existence in the same way as my Earth body, there is no physical previous me so this personB is all there is of my physical and psychological self. My energy cannot be created or destroyed, so personA being transferred in a different form and reassembling into personB is no different than how our cells are going through death and life cycles. The relation continues and therefore I continue.
As others have mentioned, Branch-line is more complicated and harder to accept. I agree with Annie’s point that the knowledge that your replica exists disrupts the continuity of consciousness and makes the replicas have different future experience. I initially thought of this as if twins were separated, both were given the same genetic code and both would have the same slate of psychological experiences. Once there are two, they cannot be the same. However, I also questioned if the replica did not know the original existed and then the original dies of heart failure, the replica is basically the same as the replica in the simple tele transportation problem. I guess what I have trouble with is that hypothetically in the simple problem, the person’s own energy could be transferred to this personB but with branch-line there are two different people made up of equal but different energy. Maybe I misinterpreted. Regardless, I would agree with Parfit that if all my parts and my psychological self were reassembled somewhere that is survival of myself and my genes. My could be me and would be able to pass down who I am. Maybe it really does not matter.
February 27, 2014 at 8:38 pm
Parfit’s telentransportation scenarios were very thought provoking- very bizarre to try to imagine as a real-life possibility. At first, the scenarios were slightly repulsive to me. I did not like imagining this type of world, where peoples’ bodies were destroyed and put back together. Just imagining a world where living beings could be synthesized using technology was hard to wrap my head around. But after putting some thought to these ideas, I have found that I agree with Parfit’s solutions to the simple teletransportation thought experiment. What I believe is most important to identity is continuous consciousness, or at least perceived continuous consciousness. I agree with Parfit that this relation, or “R”, does not have to rely on memory, but instead a psychological connection that can be made up of intentions, beliefs, or desires. In the scenario of the simple teletransportation, this psychological connection is upheld, and so is the perception of continuous consciousness. Even though the body that enters the teletransporter is destroyed, they have a psychological connection with the person that entered the transporter- they have a perception that they only lost consciousness for a moment and awoke unchanged, just like the experience one feels when awaking from anesthesia after undergoing surgery.
However, Parfit’s branch-line teletransportation thought experiment, and his conclusions, were much harder for me to comprehend. The idea of having two of myself living at once is unsettling, and after considering this example, and Parfit’s conclusions, I did not quite know what to think. The first conclusion I came to was that these two people could not the same person, because their streams of consciousness are different. The moment they begin to have different experiences, memories, and psychological connections, I don’t believe they could be the same “person.” However, we are never really told what the person who came out on mars is experiencing. Perhaps that person will still have all the experiences of the person who entered the teletransporter, and that person will have an uninterrupted stream of consciousness. Did they realize something went wrong, and that there was still another one of “them” on earth, or do they go on living their life, just as they had every other time they used the teletransporter? If they never realize that there is another “them” still on earth that will die in a day or so, then they are essentially still “themselves”. In this sense, I agree with Parfit that the uniqueness clause is relatively unimportant compared to R. As long as someone is experiencing a connected psychological experience, there is really nothing else that matters. Even they did find out that their previous body were still living on earth, that really does not change the fact that they are living a psychologically “connected” life. In the end, does it matter that there is another “person” that resulted from the same original being? Just like in the “My division” scenario brought up by Parfit, I believe that both resulting beings can originate from the same one being, and both be continuous with that previous self, yet from that point on differ. And in the end, ass weird as it is to say, I think I agree with Parfit that nothing really matters except a connected psychological consciousness, a relation “R” between beings.
February 27, 2014 at 8:37 pm
Considering that Parfit works from a base of the brain without some sort of mind/soul substance, I think that he does arrive at the strongest solution to his problems, for the most part. In both the simple and branch line experiments, he questions whether personal identity can survive situations in which information is transferred to different matter in order to rebuild the person. This is important, because in his argument even psychological things (ie memories and beliefs) are rooted in the physical. They’re not exact pieces of matter, but rather states or patterns in which the matter behaves. Furthermore, at the most basic level, there is no difference between the matter in inanimate and the matter in living brains. Taking this into consideration, it seems that the branch line experiment is not even completely necessary to arrive at his final conclusion regarding R and the absence of a personal identity as we like to imagine it.
The key to the strength of his conclusion is that, in reality, we change. The atoms in our bodies, our beliefs, our thoughts, even the subtle connections between neurons change with every thought. The fact that we persist over time means that we must change, or else it would essentially be the same as not moving forward with time. Yet, this constant change is no different from the teletransporter in Parfit’s experiment. This actually reminded me of something Descartes mentioned in his Meditations. Descartes stated “because the entire span of one’s life can be divided into countless parts, each one wholly independent of the rest, it does not follow from the fact that I existed a short time ago that I must exist now, unless some cause, as it were, creates me all over again at this moment, that is to say, which preserves me” (III.49). In this case Descartes is referring to God, but there could be some sort of cosmic teletransporter that constantly recreates everything at each “now point.” It is the information exhibited by the matter, not the matter itself that is important. Yet that information/behavior (that becomes the psychological aspect of a person) still relies on the existence of matter, so it must change too. There cannot be an unchanging essence, so there numerical identity cannot persist over time.
On a somewhat related note, yesterday there was a lecture given by Fusan Ryushin on the Buddhist concept of death without the self, and he used a metaphor that seemed somewhat relevant to the issues we were discussing in class. If the universe was a sheet of cloth, then each person would be a tiny section of the cloth that twisted around itself until it seemed to become somewhat of a separate entity (and in our case have awareness of that existence). Yet, the twist is still part of the cloth and there is no difference in material. On a practical and everyday level the twist does become an entity of its own, but on a metaphysical level it is no different from the cloth. If the twist were recreated elsewhere, it would still be just as good as the original twist ‘surviving’ and if the twist unraveled, it would still exist, just in a different state.
February 27, 2014 at 8:35 pm
I basically agree with Parfit’s answer to both the simple and branch-line teleportation cases. I especially think he is correct to assert that rather than numerical identity, it is relation R (the relation of psychological continuity) that we should really be worrying about. However, in some ways I think I am willing to go even further than Parfit, and say that not only should we not be worrying about numerical identity, the reason we shouldn’t be worrying about it because it doesn’t exist. I don’t think it makes much more sense to posit a psychological criterion of personal identity than to posit an animalist criterion of one — although I do think the psychological criterion gets us closer to the relationship we tend to THINK of as identity in the normal course of affairs, namely that between our present and past-future selves. However, I don’t think this concept answers to anything meaningful — like Parfit says, the only possible way it could would be through some vestigial dualism. For anything to endure, constant and unchanging, from one moment of our experience to the next, we would have to posit some sort of substantial Cartesian ego; a solid, first-person audience member sitting in the theatre of the mind. I don’t find this a plausible picture. None of the things that seem to make us up — sensory data, experiences, mental representations, bodily states — can be identified with this homunculus. The locus of our I-voice unfailingly eludes us; at least, this has been my experience whenever I’ve tried to look for it (in meditation, or sometimes in artistic activity). In fact, in my experience, I don’t think that the sense of being a first-person is usually present with any constancy at all. Usually there is just experience; just the psychological content itself. (It seems to me like the concept of an I-voice only emerges when this psychological content turns in on itself and starts processing itself on a meta-level. But I digress.) Anyway, if we accept this chain of reasoning, all that we are left with is the content of experience itself (and the physical state which is somehow identical or related to this content — but this is kind of a black box right now, so I’m not going to try to open it yet). It seems undeniable, to me, that these mental contents are constantly in flux. The same is true of the body they correspond to: our physical organism is constantly recycling its parts and reconstituting itself with new ones. Thus, my mental-physical state in one moment is as different from that state in the next moment, as, say, two different frames in a time-lapse weather simulation.
Following this argument, I agree strongly with the paragraph on the Bundle Theory which was included on our in-class handout. Replication is ‘about as bad’ as ordinary survival. Relation R is, essentially, the relation we hold with our past and future selves, and there is no special extra ingredient or ‘further fact’, beyond continuance of psychological state, that we are referring to when we talk about being the same person today as yesterday, or when we were five. Personhood is a similarity cluster rather than a numerical entity. Thus it doesn’t matter whether you have one copy or two copies or whatever — none of them will be you, of course, but ‘you’ wouldn’t have been you either.
February 27, 2014 at 8:34 pm
I do believe that Parfit gave the right solutions to his teletransportation thought experiments.
The branch-line teletransportation (BT) offers a fairly straightforward solution, at least to me. It seems quite clear that because there are two bodies that originated from the same person and exist at the same time, they cannot be identical. The moment that Person B walks out on Mars and Person C walks out on Earth (both originating from Person A), they become different people and therefore have different identities. As soon as they start having experiences and creating memories independent from one another they are distinctly different. They do not share any sort of psychological or physical linkage; one does not feel pain when the other is pinched. They therefore cannot be identical because they are not continuous in any sense after they start taking actions and thinking thoughts independently of one another. Parfit says that they are not identical because this violates the “uniqueness condition” that he has presented, and I would agree.
The simple teletransportation (ST) case is not so clear-cut. A person on Earth is copied and then reproduced on Mars, after the original body on Earth is destroyed. Are these two people identical? The instinctual answer is to say no. The body that was created on Earth by a human mother (supposedly) has been destroyed and then recreated somewhere entirely different. If we think about origin as one of the things that defines identity, then this would violate that. I understand how this process could be a bit disconcerting. It is unnerving to think about your body being destroyed in one place and then somehow reappearing, in the exact form, somewhere else. The same, but most certainly different. Parfit argues that the answer to this case would be indeterminate, meaning that the people could be identical or not, and I would agree with that. He argues that it does not really matter what the outcome of the situation is because what really matters is psychological continuity. Parfit even says that personal identity does not hold any weight against psychological continuity. While I do agree mostly with that, I would also not be so quick to dismiss certain aspects of our identity. I do believe that humans transcend their bodies but I believe that the ability to transcend has to originate from our bodies – our unique bodies. And so then I am tempted to say that in the case of ST, the person who entered the machine on Earth would be the same as the one on Mars because although the body itself does not have the same origin, it is still physically exactly the same. And the person would still be psychologically continuous. It would be more problematic if the person left on Mars in a different body. Then I would argue that they are not the same, even though the person on Mars would still be psychologically continuous with the one on Earth. I think, then, that there has to be some sort of interaction with body and mind and so while I am not completely satisfied with Parfit’s theory about the self, I think he has offered the closest solution to what I believe to be the definition of self and personal identity.
February 27, 2014 at 8:28 pm
Parfit offers a surprising solution to the questions brought up by his teletransportation experiment. Where many other philosophers try to parse out this seemingly unanswerable question, Parfit goes the next step, by leaving it unanswered rather than struggling with it. When it seems plausible that there would be more than one “you” surviving the branch-line version of teletransportation, Parfit suggests that it really doesn’t matter which one of these is the real you. His arguments are logical in describing the resulting bodies, and it is hard to definitively argue one way or the other. Even in the main line teletransportation, which seems like it would be “you” on the other side, there is a gap in the continuity of time and space upon which we tend to define our existence. I think he is very clever in taking it the way he does, rather than trying to decide whether or not “you” still exist; he doesn’t try to argue for how we define personal identity.
As initially shocking as his declaration is-that personal identity doesn’t matter-after a letting it set in a bit, it starts to make sense. Really, all my life is is a series of relations, between my mind and body, my mind and itself, between me and other people. It makes sense then that I can define myself (which doesn’t matter) by this string of relations, whether or not they are continuous in time and space. The way we create meaning is in relation to the outside world, and so it is reasonable to think of this string of relations continuing after our “death” in a different manner. In the most physical way, my children will live on in relation to my life, as well as in the ways I’ve interacted with other people. So although this string is no longer anchored to a single physical being, it still continues. The actual “me” doesn’t matter, I am defined by the varied ways this mind and body I claim to inhabit interacts with the rest of what may or may not exist.
It does feel like a bit of a cop out though, similar to religion in my mind, a way to create peace of mind in face of our mortality. It marks an ill-ease at leaving this question unanswered, as I think it remains.
February 27, 2014 at 8:27 pm
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
I disagree with Parfit’s solution of the branch-like teletransportation that neither the person who came out of the machine on earth (body B) nor the person who came out on mars (body c) is the same person as the one went in the machine at the very beginning (body A). Although his argument about the violation of the uniqueness clause sounds logical when applied to the bran-line teletransportation as one event, the argument does not really make sense if we consider this teletransportation as 2 loosely connected events: event 1 starts from body A walking in the machine and ends at body B coming out of the machine and event 2 starts from then to when body C emerges from on mars. Considering event 1 alone, we find it really hard to convince ourselves that body A and body B are different persons because event 1 is directly comparable to a scenario where a person gets in an MRI scanner and lies there for a couple minutes before getting out realizing there was something wrong with the machine. In this case, it is unlikely that anyone would argue against the fact that the person who got out of the scanner and the person who went are 2 different individuals. Linking this back to Parfit’s branch-line teletransportation, we can conclude that body A and body B are the same, contradicting Parfit’s interpretation.
February 27, 2014 at 8:27 pm
There is an old economics joke that is particularly relevant in discussing Parfit’s arguments. An engineer, a chemist, and an economist, are stuck on a desert island, surrounded by cans of food, but do not have a can-opener. The engineer says, “If we jam a sharp piece of rock at the right angle, we should be able to pop open the can.” The chemist says, “That’s rubbish. By creating the right fire conditions and heating gently, we can open the cans and warm our food properly.” The economist says, “Let’s assume we have a can opener.”
This same vein of absurdity can be encapsulated by Parfit’s thought experiments, designed to challenge our deeply held conceptions of self. I believe that Parfit does make a mediocre argument for the simple and branch-line teletransportation, but only in his universe. What if the replicator accidentally places a single hair follicle astray? What if the replicant falsely remembers his 2nd grade math teacher as Ms. Johnson instead of the true Ms. Smith? Is there a strong enough psychological continuity for Parfit to declare that the two have the same personal identity? Parfit argues through his equation PI=R+U, that these small differences in uniqueness have little bearing on personal identity, but I would disagree. Does 98+2=98? No, of course not! Despite the magnitude of R, U still exists and negates his point, “ U makes no difference to the value of R.” (450) I believe this brushing aside to be a fundamentally naïve claim.
Our bodies move temporally through time and space, sloughing off some molecules and accumulating others. I imagine a worm eating its way through soft dirt at a constant rate. Parfit stipulates that if we stop this temporal streak, capture it instantaneously, and send it across the solar system, the same personal identity will emerge. This disjunction of being in time does not allow the replica to be inherently the same being. In the branch line hypothesis, when person A steps in and is scanned, person A does not emerge. This is due to the Heisenberg uncertainty principal that states we cannot know the velocity and the position of an electron at the same time. By observing all of the electrons in the body simultaneously, they are fundamentally altered and we can say the replica on Mars (B) and the scanned man on Earth (C) are each different from the man who walked in (A).
I believe that Parfit makes interesting and thought-provoking claims, but he forces the reader to makes leaps of faith against essential scientific propostions that would cause his argument to crumble.
February 27, 2014 at 8:02 pm
Initially I agreed with Parfit wholeheartedly, accepting his argument for the Psychological Criterion to build upon Locke’s Memory Criterion. In the case everyday living, Parfit’s idea of psychological continuity seems to be more in agreement with what many people would naturally lean towards but perhaps not have the specific vocabulary to express (myself included).
Things get more complicated with the simple teletransportation (STT) example. There is something that is viscerally frightening about having one’s body destroyed even if survival is guaranteed. Yet, listening to Parfit as the narrator describing waking up on Mars is reassuring; the logic of psychological continuity remains intact and expresses its relevance.
It is the branch-line teletransportation (BTT) example that forces one to reconsider these last thoughts and reevaluate the nature of the transportation Parfit is suggesting. How can one version of a person be teleported to Mars, while another remains on Earth? My interpretation of this dilemma is that the Earth body (EB) is the original, or true “person” while the Mars body (MB) is the product of an accelerated birth –a being is created who is analogous to the original yet in reality this being only came into existence within the milliseconds it took to rearrange formerly inanimate matter. The MB may look back in its memory and think, “I was teletransported to Mars and this is how I came to be standing here” but really this being was created using a blueprint of zeros and ones zipping across space at the speed of light. A Cartesian ego or soul is not necessary for this claim to be true. We exist, with or without souls, but we don’t exist (in this world, as far as we know) without bodies. Neurons fire, thoughts are created, the functional units of a person move and act in all the right ways, but fundamentally OP and MB are not the same consciousness (perhaps there is a better word for this). If you snuff a candle and light it again, is it the same flame? By all the ways of counting it is, (the candle is physically the same, it follows the same rules of physics, etc.) except that there is something that feels wrong about not acknowledging the transition.
Another thought: knowing the outcome of BTT, I highly doubt that MB would undertake a journey back to Earth using this method.
February 27, 2014 at 7:46 pm
Parfit offers four convincing arguments for solutions to his simple and Branch-Time teletransportation. They were convincing enough that by the end I found myself nodding along to his final point that my existence and life as I perceive it is simply a chain of psychological states and nothing more. But none of his theses, nor that conclusion, address the possibility that identity consists in body, as Gretchen Weirob argues. His argument rests on the premise that continuity of identity/existence, as we experience it, exists in psychological continuity and a “relation R” which somehow connects through a chain of psychological experiences.
In his thought experiment, Parfit decides to use simple teletransportation, in which his body is destroyed on Earth and made out of new matter on Mars, because his wife has done so many times and is okay. But what is his measure of “there is nothing wrong with her”(444)? Is it that she appears the same? Her mannerisms and outward behaviors indicate that she is the same person who identifies as his wife as she was before? The fact that she tells him she is his wife, can speak of past experiences, and says she remembers being his wife? Is it the fact that she looks the same as his wife did before simple teletransport?
Based on how he defines continuity through time, Parfit would most likely suggest that all of the above (aside from the looks) would qualify as reliable measures of what it means to exist as the “same” being through the teletransportation. We can believe that she is the same person if her external expressions of her internal psychological experience express no doubt of her “sameness” from before teletransport. What she thinks is only what matters.
But Gretchen Weirob in the Dialogue on Personal Identity invites the possibility that any apparent psychological continuity could be the result of false memories, a trick of the mind, or a delusion that exists in this new body is not an accurate representation of connectedness. That imposter has had those experiences implanted in his/her head , so that it seems that she comes from the same continuous experience as the original body. But what if her thoughts are akin to new thoughts just being born? Parfit asserts that continuity exists as a chain of psychological memories or states (like intention or desire) based on our internal experiences of who we are, and nothing more. However, I was still left wondering, despite all of the different definitions of personal identity offered, whether I would be comfortable calling a new body version of a friend who was teletransported “you” with the same meaning it had pre-transport. I don’t think I would trust that person like I did my pre-transport friend.
February 27, 2014 at 7:32 pm
I disagree with both of Parfit’s solutions to his teletransportation scenarios, because I disagree with his definition of identity.
In the first, “simple” case (the one in which a person is scanned, destroyed, and virtually identically reconstructed elsewhere), I think that the product of the procedure is indeed the exact same person that originally entered the machine. This makes sense to me, because I choose to define a person as a psychologically capable human whose memories go back in time and are real; when I say “real,” I don’t necessarily mean that the memories are “true,” because whether they are in accordance with reality does not change the fact that they inform the person’s mind. Thus, in the simple case, the person who exits the machine is the same person who entered it, and the fact that this person’s original body was destroyed is irrelevant to the person’s identity, as long as the new body is an exact replica of the last. In this sense, I disagree that the new body’s identity is “indeterminate.”
Parfit’s “branch-line” case argument also makes little sense to me. He argues that, when the original person steps into the machine, he is duplicated and rebuilt elsewhere while maintaining his initial state as well (temporarily). Parfit believes that neither of these two new people are the original person, based on the rule that two identical beings cannot coexist. My response to this argument is that while the two new bodies are at least initially identical, the moment they started living their own, separate lives, they were different beings. And, furthermore, I believe that these two new people are BOTH identical to the original person, but that they are not identical to each other. In other words, their relationships are backwards with their original self, much in the same way that a normal, undisputed person’s identity is shaped by their former experiences as well as their current one. So, I think their can exist two new people who came from the same one in this case, and I don’t have a problem with this logic.
Incidentally, I think a good comparison is the case of identical twins. This is not terribly uncommon and it happens in real life, so it is a good example. Depending on when one defines the beginning of a person, it could be argued that at one point (a very, very early stage) two identical twins were the exact same “person.” Still, their divergent paths and experiences made it so that they were different people, undebatably. I don’t see how this is different from the branch-line case, but no one would dispute that two identical twins are indeed different people.
February 27, 2014 at 7:30 pm
I found the Parfit selections interesting because it left me with almost exactly equal doubts and supports of animalism and psychological theory, but little faith in reductionist theory. In the simple teletransportation case, Parfit sold me on the idea that the Mars replica shared his original identity. If the chain of consciousness is continuous and each cell of the body is exactly the same, how could we argue that the replica and the original are not one in the same? This case contains elements of both theories, because psychological continuity is maintained, and it can be made animalist by connecting the idea that memory is dependent on neurological plasticity (so continuity is maintained by virtue of the fact that exact cellular structure is maintained).
Then Parfit introduces the branch-line teletransportation scenario, which seems to completely contradict every conclusion I had drawn from the previous situation. I think that even upon first reading, it is intuitively apparent that, if A goes in and B and C come out, A is gone and B and C are different individuals with ‘new’ identities. However, as Parfit points out, this indicates an attachment to a ‘further fact’ because both B and C are psychologically and physically continuous with A and therefore the same according to both animalism and psychological theory. Up until this point in the reading, Parfit had sold me on every idea he presented, but I found it difficult to buy the idea that the U in his equation “does not matter, or matters only a little (450).” I found myself more taken with the idea that our continued existence “must be all or nothing,” which he immediately and somewhat jarringly chases with “This is not true (451).” It seemed to me that his only argument to support this bold statement was based more on what he desired to be true than on logic or reason. Perhaps I’m oversimplifying, but he seemed to say that our continued existence can be found in the loose relationships between our current experiences and the future experiences of others and that he embraced this belief because it makes his death “seem less bad.”
Overall, I think the teletransportation scenarios raised some really interesting questions about the intersection of other identity theories, but Parfit’s follow up arguments for the strengths of reductionism did not resonate with me. For a view that seems to reject and even scorn the sentimentality of a Cartesian soul, Parfit’s theory seemed to rely quite heavily on emotional arguments rather than reason.
February 27, 2014 at 7:21 pm
I believe that Derek Parfit does provide the correct solutions to his teletransportation thought experiments. The thought experiments provide us with a clear illustration of why it is problematic to attribute personal identity to an immaterial mental substance or ego. They also serve to show why Locke’s criterion of psychological continuity through memory is insufficient for describing personal identity. Above all, however, Parfit’s examples present the bizarre, but plausible, idea that personal identity may sometimes be indeterminate.
In his main-line thought experiment, it is very easy to say that the person on Mars is identical to the original person on Earth who gets into the teletransporter. Even with the belief in a Cartesian ego, it would make sense that the ego would follow the body and remain with it after it is teletransported. This becomes less apparent in the branch-line teletransportation thought experiment where the original person’s teletransportation results in the creation of an additional person rather than a replacement. In this case, which body would the Cartesian ego follow? It seems obvious that this ego, if it exists, would remain with the original body, rather than the teletransported one on Mars. And so, our original assumptions from the main-line thought experiment about the transferal of the Cartesian ego have been proven false.
It seems that admitting the existence of a Cartesian ego results in paradoxical situations. Therefore, it cannot exist, and our identity cannot be tied to it. This also means that identity can be indeterminate, especially in the case of the branch experiment where Bodies B and C are both continuous with Body A, but are not psychologically linked to each other. In these cases, we can see that the idea of “consciousness” is incompatible with and irrelevant to identity.
February 27, 2014 at 7:17 pm
Does Parfit give the right solutions to his simple branch-line teletransportation thought experiments? Why/why not?
I believe that Parfit’s arguments are logical and so his solutions to the simple and the brain-like teletransportation experiments follow from his arguments. However, whether or not they are ‘right’ is more difficult to answer. I find that his logic is very convincing and I agree with his modifications of Locke that include broadening the psychological connection beyond memory and including overlapping chains of physical connections. The part that challenges some of my own internal beliefs is the branch-like teletransportation case. According to Parfit’s arguments, his conclusion in this case is that relation R, psychological continuity, is survival because this relation, and not personal identity, which requires uniqueness, is what is important. If you accept the argument that personal identity is not what matters, then his conclusion in this case is right. His argument therefore isn’t an ontological argument about what exists or what makes up these complex relations, but is instead about what is important.
I think that he dismisses uniqueness too easily. His claim is that it is an artifact of usage of the term personal identity and not as important as we think it is. Perhaps this is because our culture is a highly individualistic culture, which is reflected even in the government. That could be why this argument is unsettling. Personal identity and setting oneself apart from others is very important in our culture, which makes it hard to accept an argument where uniqueness is nonessential. Even if he is correct that uniqueness is a linguistic artifact that should not be central to psychological continuity and personal identity, the result of the terms being used in the way that they are is that for many people, including myself, it is very difficult to separate uniqueness and disregard it as a nonessential component. Therefore, my main objection is to the value thesis and Parfit’s claim that uniqueness, and thus personal identity, is not as important as psychological continuity. The consequence of this objection is that I believe that in the case of the branchlike teletransportation, his conclusion is incorrect and that this situation is not analogous to survival.
February 27, 2014 at 7:02 pm
Does Parfit give the right solutions to his simple branch-line teletransportation thought experiments? Why/why not?
Parfit proposes a modern version of the idea of the self, modifying Locke’s view, in the selection from Reasons & Persons. Unlike Locke’s “direct connections”, Parfit’s theory allows for overlapping chains of psychological connections. He presents his theory with examples of theoretical simple and branch-line teletransportations. His argument concerning the identities of the original body and the copy made on Mars is supported with the idea of a different cause of one’s psychological continuity. The copied being still retains memories from before, even with a replicated body. In this case, psychological continuity is not necessarily a barrier to you not considering the “other” person as the “same” person. However, in Parfit’s branch-line example, neither the copy existing on Mars nor the “damaged” body produced after the teletransportation is, in Parfit’s eyes, identical to the original person. Due to the fact that both the body on Earth and the copy on Mars exist at the same time, albeit in different locations, the uniqueness condition is violated. Parfit believes that personal identity, as we use it, is transitive. In conclusion, he thinks that psychological continuity trumps personal identity.
Although Parfit presents a strong argument, his overarching concept of the inability to determine whether the copied body is the original person leaves the reader hanging. He is denying us the ability to numerically identify the idea of the self. This “grey area” does not provide us with concrete answers, but does account for varying degrees of continuity and connections.
Considering the entirety of Parfit’s argument, I agree that the idea of the self cannot be simply, numerically defined. However, I disagree with his dismissal of the concept of personal identity. I have trouble conceptualizing the idea that with the death of the “damaged” body (in Parfit’s branch-line teletransportation example), some aspect of psychological continuity lives on through the copied being on Mars. With different bodies in different environments, how can continuity exist? How is the idea that this other being is continuing his life as a “copy” of your being comforting in that you might still “live on” in some way or another? I believe that when the “damaged” body dies, the “copy” will no longer be able to be associated with another being. This body on Mars will follow its own path, even though there are similarities upon its origination. The link disappears when the “original” no longer lives on.
February 27, 2014 at 6:50 pm
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
Although this may be the minority opinion, I found Derek Parfit’s explanations and conclusions very refreshing. Due to our human patterns of recognizing a person by their appearance, contextual setting and personality, it is hard to formulate a theory like Parfit’s on personal identity without considering objections. As Nathan touched on his his response below, I like how Parfit “tells it like it is.” Although he offered no definitive conclusion, his rhetorical concluding remarks were satisfying enough for me. Does it really matter if it is our same body or not? If another being is psychologically continuous with us then isn’t that good enough? In Parfit’s eyes, it is indeterminate whether Person A is Body B or whether Body A is exactly identical to Body B. The answer could be yes or the answer could be no. It doesn’t really matter and in some way I found this the most settling conclusion to these teletransportation experiments.
Due to the more direct psychological continuation of the simple teletransportation problem, I can see people would find this a more pleasing idea. Their psychological continuation would be much more present and although the body may change, the individual’s consciousness remains continuous and the same. However, in the branch line teletransportation, consciousness from one body to the next diverges. I think the process of letting go of our consciousness is the most unsettling event for humans to comprehend. This attachment to our psychological consciousness is why we have to work everyday to repress our fear of death. In thinking about Parfit’s stance, Animalism comes to mind. Supporters of this theory would argue that our minds and bodies are so connected that we can not exist anywhere else outside of our bodies. But for those that find objections to this can agree that there is something else outside of our physical brains that are allowing us to think the way we do. In light of our consciousness being somewhat separate from our bodies, then we can not fully object to the idea of our consciousness existing somewhere else.
As previous posts also mentioned, I feel that Relation R is very important to Parfit’s conclusions as well. Psychological continuity is desired by humans in their struggle to let go of their consciousness. The question that comes to mind is how can we really determine the uniqueness of our current consciousness from previous consciousness that may have embodied other people previously? If we can not be completely sure that our consciousness is unique to us as individuals or to our bodies, then how can we disprove the continuity of our consciousness elsewhere after we die? These are questions I don’t know if we will ever have the answer to. But for me, in terms of embracing my death one day, it is way more settling to know I will continue to exist at least psychologically somewhere else.
February 27, 2014 at 6:36 pm
Parfit’s Selections from Reasons and Persons introduces the thought experiment of simple vs. branch-line teletransportation. As implied by the name, the simple teletransportation example reads in a relatively straightforward manner. Body A enters the transporter and the consciousness responsible for body A will awaken in an identical body on Mars. This become more complicated though when the question is introduced as to whether these two bodies are the same person. Parfit takes an interesting stance on this matter; claiming that they could be, yet they could not be, and ultimately that it doesn’t really matter if they are or not. The last segment of this argument, however, relies on one not believing in what he refers to as a “further fact” – which I took to be analogous to the soul. This is where I found myself starting to disagree with Parfit, in that I do fundamentally believe in a soul and thus, to me, the result of whether these two bodies do/do not encompass the same person or identity does matter. I also thought that Parfit seemed to contradict himself slightly later in the article when, while presenting the division analogy, he claims that “I would survive if my brain was successfully transplanted.” Although I may be misinterpreting his argument, it came off to me as if he was implicating the brain as the locus of an identity, or an “I”. If this were to be true, then it seems as if not only would the answer to his question matter, but that they wouldn’t be the same person as the original brain of Body A was destroyed during transportation (unless he believes that all that is required to perfectly replicate the brain is the recording of the exact state of all of its cells).
In comparison, his branch-line anecdote provides a more perplexing, yet ultimately resolvable (by his standards) problem. In this example, body A enters the teletransporter and is seemingly identical to both bodies B (on Mars) and C (on Earth post-teletransportation). However, Parfit is quick to distinguish these entities having the same bodies and subsequently being the same people/having the same identity. In the psychological criterion that he sets forth to support an extension of Locke’s argument, he states that psychological continuity can only be present if there does not exist a different person who is also psychologically continuous with the original person (claim 4 – the “uniqueness clause”). Branch-line teletransportation appears to directly violate such a clause, and thus implies that neither body B nor body C is the same person as body A. He also brings in the idea of exact similarity vs. numerical identity; in which he posits that, although body A may be qualitatively identical to bodies B and C (via the club/nation argument), that they are two different people, and thus not numerically identical since the life of one overlaps with the lives of the others. I agree wholeheartedly with Parfit here that neither B/C is identical to A, however for a different, more Cartesian, reason. The idea that one person can be occupying more than one place in space and/or time is something that I have always deemed, at its core, impossible – at least in the metaphysical universe that I believe us to exist in. In reality, this may be more of a difference in language and consequently more analogous to his “uniqueness problem” than I had originally thought. One thing that is for certain though – although I should hesitate to use such a word in a discussion like this – is that Parfit’s thought experiment got me thinking more deeply about the self and my identity than I had previously believed to be possible.
February 27, 2014 at 6:35 pm
Parfit’s teleportation example calls attention to the modifications that he has made to Locke’s theory of personal identity. By deviating from Locke’s initial memory criterion, Parfit steps away from the notion that one’s continuous memory is what allows them to persist over time; instead, he focuses on a different psychological connectedness. By presenting his modifications in the form of the teleportation example, Parfit is able to demonstrate the effectiveness of his changes to Locke’s theory and also call attention to several complications. To this end, I believe that Parfit gives some correct solutions to the simple and branch-line thought experiments.
With respect to the simple thought experiment, I believe that Parfit’s solution is in line with his definition of personal identity. In defining personal identity, he puts an emphasis on allowing for overlap in psychological connections and broadening psychological connections to include continuity of belief, desires, and intentions. With these in mind, it seems to me that in the simple thought experiment the person exiting the machine on Mars would in fact be the same person as they were on Earth. This would be the case because, despite temporal discontinuity, the bodies would contain the same psychological connections, making them the same person. However, given Parfit’s value thesis and emphasis on the relationship between psychological continuity and uniqueness, it would seem that both bodies in the simple thought experiment contain different people. These two conclusions make Parfit’s declaration of indeterminacy correct. That being said, I think that his theory may contradict itself. At the very least, I have trouble understanding the logic behind the uniqueness. Why can’t a different person Z who is psychologically continuous with Y exist?
It is in this same vein that I question Parfit’s solution to the branch-line thought experiment. If people can have different psychologically continuous stages (X and Y) over time, why can’t branch-line teleportation be described as two different stages of the same people? Parfit suggests that body B and C, the result of teleportation are not the same people as person A. If you consider B and C different stages of person A, both psychologically continuous with A, but unique from each other, why can’t they be the same person? I would argue that this flaw in the argument prevents Parfit from solving the problem of transitivity. Furthermore, I think that the solution Parfit offers for the branch-line thought experiment is flawed.
I agree with Parfit’s logic in some of his modifications to Locke’s theory; however, I disagree with the way he applies them to solve the simple and branch-line teleportation thought experiments.
February 27, 2014 at 6:14 pm
Although Parfit was in using his division of simple teletransportaiton and the branchline teletransportation to show how personal identity can be represented, I cannot find myself completely agreeing with either option. While I cannot necessarily point to one specific aspect of simple teletransportation that I find problematic, at the same time I cannot completely believe in it either. On the other hand, I know I find branchline teletranpsoration troublesome because it is not derived from the proper train of thought. Parfit admits that branchline TT does not yield two individuals that are identical; however, his explanation as to why this should not matter seems to be a cop-out answer. The value of an argument does not necessarily constitute accuracy. His reductionist proposition for understanding self-identity under the assumption that uniqueness is not important is not good support for saying why duplication is not a problem for determining personal identity. I would not agree that uniqueness is just a tenet that adds to the value of personal identity, but an essential component of what defines personal identity. His definition of personal identity confuses me because it is more emotionally based on his own preferences for how he chooses to view life rather than an argument for what is the right way.
Obviously there are several components to what creates one’s personal identity. However, unlike a burger, which will still be a burger without lettuce, the components of personal identity are all essential to the definition of personal identity. In branchline teletransporation, the two people that come out as bodies B and C are not identical to each other, however you can say that the initial person A came back out as body C (the person that ends up dying a few days late). This is because he/she has maintained the same body and mind as when he/she first entered the teletransporter. Therefore we can consider person A as having died after a few days while body B lived on in Mars. In that case, body B and body C need not be identical since person A= body C and body B is not equal to body C and therefore body B need not be identical to person A. When body B dies then, body C does not live on as person A. Parfit claims that body B and C are not identical but because of the value of considering them to be equal even though they are not unique, you can claim them to be the same person. He makes this claim because he would like to think that he lives on even after he dies, but this is not a strong enough reason to make uniqueness of factor of value rather than accuracy.
February 27, 2014 at 4:40 pm
I’m actually not quite sure what I think about Parfit’s arguments. On one hand, the idea of reductionism makes perfect sense to me, in that I think it is reasonable to assert that there isn’t really any type of “Cartesian Ego” (that is, to say that personal identity is simply composed of impersonally describable facts). On the other, I find that I cannot easily accept many of his other conclusions, particularly the ones that have to do with the teletransportation scenarios. For instance, his ‘resolution’ of the simple teletransportation situation seems like the absolute worst answer that anyone could possibly give. Based on his story, it seems clear (at least to me) that the person walking out of the transporter on mars would be the same person that walked into it on earth. After all, psychological continuity and uniqueness both seem to be maintained, so it appears as though both parts of the PI equation remain fulfilled. But even if I’m wrong (or if I’m misreading his arguments), his answer still seems terrible. What we’re looking for in a theory of personal identity, I think, is confidence, and there is nothing here to inspire confidence. I suppose that the answer technically makes sense given his theory of reductionism (if personal identity is just a set of interrelated physical and mental events, it is kind of weird to ask whether two sets of events can be counted as the same), but it’s just so… bad! If I was offered the chance to get in a teleporter, the question “am I going to survive this?” would strike me as fairly important. And Parfit’s answer, as I understand it, would be some combination of “yes and no”, “maybe”, “I have no idea”, and “it doesn’t matter.” But it does matter! If I asked the question “will the person who walks out of this teleporter be me?”, answers like “persons are indeterminate” or “there is no correct answer” would be terrifying! Again, they technically make sense, but would anyone want to hear them before pressing their own big green button?
I object to Parfit’s branching path answer as well, although this reaction is a lot less ‘visceral’ than it was in the first scenario (probably because the conditions are much more complex). Essentially, I think it seems fairly obvious that the person who walks out of the teleporter on earth is the same person that walked in. After all, nothing actually happens to the narrator as he is standing in the transporter… he walks in, the machine makes a copy of him and sends it off somewhere, and then he walks out. At no point during the story (it seems to me) does the narrator ’die’ (or even black out), and yet suddenly Parfit asserts that he no longer exists (and instead has turned into 2 different people)? That makes no intuitive sense to me. If he walked in, remained conscious the whole time, and then walked out, when did this split happen? Does it have any practical implications for the person who remains on earth? What is the point of calling the person that walked out a ‘new person’ if he is mentally and spatially continuous with the ‘old person’?
Honestly, the most intuitive way I can think about this is in terms of who the narrator is. In the single path situation, the narrator is the same throughout the whole story, and this implies that the person remains the same throughout the story as well. In the branching path scenario, by contrast, narration sticks to the ‘earth-bound person,’ and this implies both that the person who ends up on mars isn’t the same as the original person and that the person who stays on earth is the original person (since he is the one narrating the whole time). Again, I could be picking this out just because it mirrors my own beliefs, but it does seem to me to be the clearest way of thinking about these situations.
February 27, 2014 at 3:35 pm
These thought experiments are troubling, they are eerie, because they force us to consider and wrestle with the idea that who we are now may not be who we are in 20 minutes and isn’t the same person from three years ago and Parit expects us to follow with the “doesn’t really matter” conclusion. In the passage provided in our handout, the final sentence, “Ordinary survival is about as bad as being destroyed and having a Replica,” is repeated and italicized. To the average human, personal identity is a pretty important concept (flashback to teenage angst, ‘finding yourself’ in college). I like what Parfit did with these examples, he simplified personal identity by removing the expectation that weighs down the Cartesian inalterable ego and, in a sense, I agreed with him and felt freed by the end.
In a sense. If I went through a simple teleportation device and pop out on the other end, feeling and looking exactly as I did, that would probably be enough for me to discard any insecurity about whether or not I am me. ‘R’ continued. I feel like I’m me. Great, let’s get a snack. With branch-line, however, I don’t think I (we?) would be quite so relaxed. First of all, I don’t think that you can argue with the claim that AnnieA ceased to exist the moment the machine didn’t dissolve her. AnnieB left the machine with a completely different consciousness than AnnieA, and AnnieC on mars will do the same as soon as she finds out AnnieA’s body remains on Earth. Knowing of each others existence breaks the continuity of consciousness between AnnieB and AnnieC with AnnieA. That break in consciousness, that ‘R,’ matters, and I don’t think that any of the possible Annies would be able to brush it off and get a snack. ALTHOUGH, if AnnieC never found out about AnnieB living past the machine, she would keep ‘R’ intact, and AnnieB may be able to think that her own demise doesn’t matter, so long as her unaltered consciousness continues elsewhere.
February 27, 2014 at 3:16 pm
Derek Parfit’s presentation of the simple teletransportation and branch line teletransportation seemed relatively simple when I first read them. Then I thought about them a little bit more, and everything seemed a little less clear… First I will address Parfit’s answer to the branch line teletransportation model. Parfit says that body’s A, B and C in this example are not numerically identical, but they are qualitatively identically. I agree in thinking that neither A, B, or C are identical persons but that does not mean that they are not exactly similar beings. It is something like cloning. If I were to clone myself (which is essentially what is happening in this branch line example) I would still consider myself the original, and the others identical copies of myself. I do admit that the branch line model is different form cloning in the way that after (or in the instant) the teletransportation occurs, the two people start different trains of consciousness. This would mean that they are not identical, and further more, I would hesitate to say that they are even exactly similar. The second that they start adapting and reacting to stimulus of their environments in different ways, they are no longer exactly similar. With this said I bring up another thought. If person A (on earth) dies soon, in my opinion, there would not be a huge loss. There will still be a continuous memory and consciousness that exists, in the form of person C on the moon. Assuming person C can safely get back to earth and resume his normal life, all would be well. All I have just stated is in assumption that there is no soul essential to comprise a person, in addition to the obvious physical matter of the body. When the soul is brought into the discussion is where I start to doubt Parfit’s views.
In response to the simple case of teletransportation, Parfit says that it is ultimately indeterminate whether body B (the body on mars) is person A (the original person from earth). He says that we could either say that it is or is not, it is virtually the same thing. We know the facts about the situation, and it doesn’t fundamentally matter if we call an exactly similar person the same person. Parfit’s use of the example of a chess club at Middlebury was very clear and to the point. It is a good analogy to his solution to the simple teletransportation. He claims that if one is holding on to the desire to get a yes or no answer, they would be holding on to the idea of a soul. The idea of a soul brings up an interesting thought for me. At first glace I think I agree with what Parfit says, in that it doesn’t matter what we call body B, because we know the important facts surrounding it. It gets more complicated for me when I start thinking about the existence of a soul. Having a soul or some other immaterial consciousness guiding us would be an argument against indeterminism, because this consciousness would not be with the new body on mars. Or at least we cannot prove that it will be. I personally think that a soul may exist, but I am not positive how it intertwines with the matter that makes up a human.
February 27, 2014 at 1:28 pm
Does Parfit give the right solutions/interpretations to his simple and branch-line teletransportation thought experiments?
The simple teletransportation thought experiment is, indeed, simple and not particularly difficult to grapple with. Does the same person come out as went in? Is Body A at T2 the same person as Body A at T1? Parfit says yes, no, and it doesn’t matter. I agree with him a pro pos the club analogy. I always find myself understanding and enjoying philosophers who “call it like it is”. I believe there is sometimes as much soundness to an argument that posits, “Well, we can all understand that, and see the facts, and so it doesn’t really matter”, as there is to one that follows the rules of formal logic. If every single cell of my body is disintegrated and then decoded and reconstructed, in such a way that my consciousness is exactly preserved despite a momentary blip, who can argue that the duplicate is not the same as me? Further, who can argue that the duplicate is the same as me? I say, any man, and all at once, and that is satisfactory for me.
In the branch-line thought experiment I am also mostly persuaded. Body A is the same person as Body B (by an extension of the simple case), and Body A is also the same as Body C (also by an extension of the simple case), but who could possibly argue that Body B is the same as Body C? Who could argue that two things that exist independently of one another and simultaneously occupy different parts of space are the same thing? The very idea goes against our entire system of logic down to the most fundamental axioms of mathematical set theory. So what, then, does happen? Well, Parfit says it doesn’t matter and we shouldn’t care. The fact that we are irked by this scenario is a remnant of some ill-informed and unconscious desire for a Cartesian ego which, as Parfit posits, simply doesn’t make sense. What matters in determining “personhood” is psychological continuity. So if A is pcontinuous with B and A is also pcontinuous with C, that should be enough to explain who is who. Each is A, but neither is the other. The only obstacle to grappling with this is spiritual.
What would happen, now, if B and C met each other face to face, person to person? I’ll leave that to science fiction.