This is a thought-provoking thought experiment. But why assume that psychological continuity depends on language? Why not start from subjective experience itself? Subjective experience is real—it’s not merely a linguistic construction. It’s the most immediate reality we have. And it’s physically real too, in the sense that it arises from whatever physical processes generate consciousness.
Now imagine running this experiment on a non-linguistic but subjectively aware organism—say, a frog. If the frog’s mind were duplicated, both resulting frog-minds would likely experience uninterrupted continuity, as if nothing unusual had occurred.
Coming back to the title of your essay—“What If You Were Duplicated by a Transporter Malfunction? Or: Why You Still Don’t Exist!”—your conclusion seems to rest on the idea that neither of the two post-duplication individuals can claim to be the original. But why would that be a requirement?
This reasoning seems to exclude time as a relevant factor. Before the duplication, there was only one me—the original. After the event, there are now two of me. And each one experiences continuity of mind with that original, even if their subjective trajectories begin to diverge from that moment onward.
Sure, their experiences of self will evolve in different directions—but that doesn’t mean they wouldn’t exist. The fact that the self is dynamic doesn’t make it illusory or nonexistent. In other words, this is not specific to being someone. So, this leads me to another experiment. What if a rock was duplicated in the same way. Would you also conclude that it didn't exist?
Hey, thanks for the comment. I'll address a few claims separately. First, you ask why I think that psychological continuity depends on language. The answer here is just that I don't! I say that there are language-independent facts about mental states, in which I include conscious states, as well as about their relations.
One such relation is that some conscious states are continuous with others in the sense you describe. At each moment, there are memories of the preceding few moments as well as anticipations of the next few moments such that no interruptions are perceived. I grant all of that. None of these facts depends on language.
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Second, you ask why two post-fission individuals can't both claim to be the original. Well, the answer here, which I do point out above, is that it doesn't seem to make any sense to say that two distinct individuals that can occupy different points in space, make separate decisions, and so on, are *one and the same person.*
Suppose you have been duplicated. You are at work. Your duplicate is visiting the Eiffel Tower. Your wife calls. She asks, "Hi, where are you?" Is the correct answer that you're at work? Or that you're both at work and at the Eiffel Tower? If you think the former, then you agree that the referent of "you" isn't *two people*!
Let's take it from a different angle. Suppose that you and your duplicate were both at a concert. There are 98 people there, plus you and your duplicate. An employee counts heads. Should he say there are 100 people there? Or 99? If your answer is 100, then you agree that you aren't one and the same person!
Maybe you think this is just because he's not aware of your situation. Suppose you were to go up to him and clarify. You explain that you aren't identical twins. Instead, you're duplicates. Up until just two years ago, you didn't have separate streams of consciousness at all. Do you think now he should change his answer?
Many philosophers would claim that it'd be straightforwardly contradictory to claim that you and your duplicate are one and the same person. Others, would only claim that it's stretching the concept of a person beyond what it can plausibly bear. I'm pretty neutral between the two interpretations, but it's pretty clear that one of the two is correct!
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Third, you ask whether, if a rock were duplicated, I would claim that there's no rock. No, of course not (though see below)! But I would claim that the two rocks aren't *one and the same rock*! That again seems either to be straightforwardly contradiction (two rocks are one rock, and so not two rocks) or else to stretch the concept of *a* rock implausibly.
Now if you were to ask me which one was *the original* rock, *now* I would say *there's no fact about that. And one way I'd support that conclusion is with the quadrilemma presented in this piece. If there were such a fact, there'd be a clear answer to which of the two, if either, is the original rock. But there is no answer. So there's no fact.
As a matter of fact, I would claim that the existence of rocks is language-dependent too. But of course, the loosely defined bundle of physical states we refer to by the term "rock" aren't language-dependent. There's some at least theoretical level of description—subatomic particles? quantum waves functions?—at which they are independent of language.
The same is true of persons. There are physical states that are, at some level of description, independent of language. There are mental states that are, whether identical with those states or supervenient on them or whatever, also independent of language. And there are facts about their relations. But there are no facts about persons over and above those.
Thanks for your reply! You're making a point, if I understand correctly, about the distinction between our descriptions of the world (for example, a “loosely defined bundle of physical states” we refer to with the term rock) and the ‘actual things’—which you describe as “facts” about mental or physical states or their relations. Right?
And then you use the malfunction thought experiment to argue that what we think of as a person is not an actual thing in that second sense, but rather one of those loosely defined bundles of facts. Right? That doesn’t strike me as strange at all—it makes a lot of sense. So much sense, in fact, that it seems to apply not just to persons, but to many other things as well. As I expected, you would argue that the existence of rocks is also language-dependent.
But the malfunction thought experiment does highlight how unsettling this distinction becomes when applied to persons. It raises the question of what, if anything, is essential to being a person. If there are no absolutely necessary facts tied to the description of a person, then we, as persons, don’t exist (in a language-independent way). Right?
Still, your hypothetical examples don’t, to me, clarify this abstract argument very well—assuming I’ve interpreted it correctly. You refer to duplication as “fission” (and also mention split-brain surgery), but it seems to me that what’s really going on in your examples is duplication. And perhaps duplication is better understood as something distinct from fission. For instance, take this example you give:
“Suppose you have been duplicated. You are at work. Your duplicate is visiting the Eiffel Tower. Your wife calls. She asks, ‘Hi, where are you?’ Is the correct answer that you’re at work? Or that you’re both at work and at the Eiffel Tower? If you think the former, then you agree that the referent of ‘you’ isn’t two people!”
Well, distinguishing duplication from fission, I’d say the correct answer depends on who has the phone and answers the call. :-)
I brought up your use of 'you' in the title—second-person—and responded from a first-person perspective.
And from that perspective: after the duplication, I—if you ask me—am either the one at work or the one at the Eiffel Tower. We both exist (we experience our existence first hand), and we were identical up to the moment of duplication. After that, there are two persons, no longer identical. I might be the one at the Eiffel Tower, or I might be the one at work. I might be the one holding the phone, or the other might have it and answer the call.
It seems to me that you are treating duplication of fission a bit ambiguously. The situation where the original is destroyed and then recreated from scratch, one version, two versions, ... is slightly different from when a duplicate is made from the original me and both continue to exist (like in your Eiffel tower example).
One final hypothetical example to illustrate this:
Suppose we had a technology for uploading you into a digital world. Suppose that the procedure is such that, during the upload process, your original body is destroyed—so you experience continuity, but now your consciousness runs digitally instead of in your brain.
But imagine something goes wrong, and the destruction doesn’t occur. Then you’re duplicated. There are now two versions of you, each with their own experience. The original you, whose brain was not destroyed, thinks: “I'm still in my body—what happened?” And the digital version of you thinks: “The transfer worked—I’ve made it into the digital world.”
Then both are informed: “There was a glitch. The original wasn’t destroyed. But a copy was made.” So the one still running on the biological brain now knows: “There’s a digital clone of me.” Meanwhile, the digital clone thinks: “I made it. But oddly enough, there’s still a version of me out there, in a body, continuing to live.”
I imagine that’s quite a disturbing realization for the digital version. But if such technology existed, I think this is what the reality would be: two versions of you, no longer identical from the moment of duplication. Do you agree that this would be the actual outcome?
Reflecting upon our discussion, it seems to me this might in part be a matter of philosophical orientation (which I was unaware about). I’m more drawn to using philosophy as a way to better understand reality, rather than using stylized or hypothetical versions of reality to make abstract philosophical points. That method has its power, of course, but to me it sometimes feels a bit too detached. So perhaps it’s not a disagreement so much as a difference in emphasis or approach.
Hey, the way you summarize my points at the start is right. On the one hand, there’s language, which includes the terms “person,” “self,” “I,” "you,” “Jan,” “Phil,” etc. On the other, there’s reality, which includes physical and mental states in certain relations.
My thesis—which really isn’t mine; I’m just trying to make ideas from Parfit and from Buddhists among other accessible—can be understood as saying that, in reality, there’s nothing that provides a necessary and sufficient condition for the application of those terms.
Now regarding the distinction between fission and duplication: As per the definitions I give, “fission” in the literature refers to any case where two continuants have an equal claim to being the original person. This is true of some of the split brain cases discussed in the literature.
More importantly here, it’s also true of duplication as I’ve described it. That is, a transporter breaks down your original body, transmits the information about your cells to a different location, and then creates two new bodies with all the same psychological states.
It is not true of of cases of duplication where a copy is made of someone, as e.g., in The Prestige. In that case, one of the two continuants clearly is the original person: The one who was in the original person’s place at the moment of duplication! Those aren’t what I’m talking about.
I’ll also use this opportunity to point out that I completely spaced when I discussed your example of the rock. If a rock is duplicated in the way described, i.e., it’s broken down, destroyed, and a perfect copy is created, then the answer is very clear: Neither of the two rocks is the original rock.
Why? Well, this is new matter. And the expression “this rock” refers to nothing else than matter in a certain configuration. Concerns about necessary and sufficient conditions for how much of the same matter there needs to be don’t even apply here, since there’s none of the same matter!
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Now regarding the case where you’re at work and your duplicate is at the Eiffel Tower: We’re discussing the referents of terms like “person,” "self,” “I,” “you,” “Jan,” “Phil,” and so on. These words are used to refer to what we take to be individual persons who we take to be identical across time.
There’s just one such individual person in the world that I pick out when I ask “Where’s Jan?” You were claiming that you and your duplicate (again, in the sense specified) are one and the same person. I was just pointing out that this would commit you to a very odd metaphysical claim.
That metaphysical claim is that this one individual person that is you is at once at work and visiting the Eiffel Tower. If “you” refers to one person and you’re claiming that both continuants are that person, then you’re committed to saying this! Your move of trying to distinguish the person being spoken to from the duplicate just seems to amount to a concession that these are two different people.
Regarding the upload case you describe, it’s is in many ways similar to the first Teletransportation case Parfit considers in Reasons and Persons. But in this case there very clearly is an answer to the question “Where is the original person?” It’s the non-uploaded physical being.
Why? Well, this just isn’t a case of fission. One of the continuants very clearly has more claim to being the original than the other. Of course, in my view, this is just a linguistic convention to refer to physical and mental states in certain causal relations.
But even if there’s no clear set of necessary and sufficient conditions for applying that convention, here there’s really no ambiguity about whether the non-uploaded physical being is the original. It clearly does still fall under our concept of what it is to be one and the same person.
But suppose that I successfully uploaded my mind and destroyed my body. Is the uploaded mind me? That is, did I survive? Or did I die? My answer is: There’s no answer to this question. The fact is that there’s now a pattern of mental states very much like mine. There are no further facts here.
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I guess I’ll just quickly comment on what you say at the end. I certainly see the task of philosophy as coming to better understand reality! And I think that these kinds of thought experiments show us one of the most important things we can learn about reality.
That thing is that there are no persons there independently of language. We can generalize this to say that there are no composite entities of any kind independently of language. These are some of the central claims about reality of certain versions of Buddhism: There is no self, everything is empty of essence.
Why is this so important? Well, I think this thesis has immense practical implications for ethics. I think it also has radical implications for how we understand our own death. Buddhists have drawn out some of these implications for millennia. More recently, Parfit and those he influenced have too.
My view is actually more radical than Parfit’s in this regard. I’m hoping to lead up to a piece on why I think this reductionist account of personal identity entails that death cannot be bad for us. I’m currently on a leave of absence and it’s not entirely clear to me whether I’m going to finish my PhD, but if I do, it’ll be on that!
I see that your duplication scenario is meant to show that “Phil” “I” or “Jan” cannot refer to a single unique entity if two perfect copies exist.
But I’d like to clarify my comment once more. You write: “You were claiming that you and your duplicate (again, in the sense specified) are one and the same person. I was just pointing out that this would commit you to a very odd metaphysical claim.“
Actually I never claimed that my duplicate and I remain one and the same person after the duplication. My position is precisely the opposite. Up to the moment of duplication (t₀) there is a single individual; from t₀ onward there are two—call them Phil‑A and Phil‑B—each with its own causal and experiential continuity. Personal identity is therefore indexed to temporal segments: continuous until the split, then branching. Your critique seems to assume that “identity across time” is an all‑or‑nothing affair, but splitting scenarios show we must assess identity relative to each time‑slice. That one name referred to a single person before t₀ does not obligate us to force both post‑t₀ continuants under the same reference.
Best of luck with further developing your ideas — in a PhD or otherwise.
Hi, loved this post super though provoking! I wanted to ask about the assumption you make early on that psychological continuity is enough for survival, and so we can treat transporters as a form of travel rather than death. What if that assumption turns out to be wrong? Given that we still don't know how subjective experience arises from physical processes is it possible?
Hey, thanks for the kind words! Well, ultimately, my claim is that the assumption doesn't matter. I start off assuming that there are indeed language-independent facts about personal identity and taking for granted that they're facts about psychological continuity, but then by the end of the piece, I claim that there are no such facts!
Suppose I use the transporter. It's a fact that the person who materializes is psychologically continuous with the one who dematerialized. It's a fact that his body is made up of cells that are qualitatively just like those that dematerialized and in causal relations that are identical. It's also a fact that those cells aren't the same ones that dematerialized.
Now is this person me? My claim is that any answer is a linguistic decision. We can say the resulting person is me and that I have a different body, or we can say that he isn't me but that he is psychological continuous with me. But those are just two ways of describing the same thing. There's no fact about which is correct.
Now the worry you seem to be raising near the end seems to be a different one. You seem to be saying something like: How do we know that the resulting being would have mental states continuous with mine given that we don't know the precise nature of the link between the physical brain and subjective conscious experience?
Well, I think we know enough to be at least fairly certain that two identical brains would produce identical mental states, including subjective states. But beyond that, if the person who materializes talks like me, remembers things that happened to me, has my habits, and so on, we can pretty safely assume he also has the accompanying subjective states!
I think something that's interesting is that the only physically plausible mechanism we know of for a transporter, quantum teleportation, necessarily destroys the original version in the process of teleportation; an accidental duplication would violate the no-cloning theorem.
I think this provides a hint that maybe there actually is something important about physical continuity in thinking about personal identity.
But even putting that aside, I still don't think you're obliged to take duplication as proving that personal identity doesn't exist; it just proves that it's non-transitive (which, I concede is still pretty weird!)
I don't see why you can't just say, me before duplication is the same as each of the two duplicates, but they're not the same as each other. That is, there are two distinct people who are each the original Riker. The original Riker used to be one person, and now he's two different people, just like (okay, fine, not just like, it's obviously way weirder) how the original Riker used to be a child but is now an adult.
But isn't identity a transitive relation by definition?
If the referent of "William Shakespeare" = the referent of "The Author of Macbeth" and the referent of "The Author of Macbeth" = the referent of "The Bard of Avon," then the referent of "William Shakespeare" the referent of "The Bard of Avon," no?
I just don't understand what what you're suggesting would mean! What exactly is this relation that you're proposing?
Well, we already know there are problems with the above in counterfactual reasoning: William Shakespeare=The author of Macbeth doesn't mean that you can replace one with the other in any sentence and have it be true.
And we already face the same issue with personal identity at different points in time: I think most people agree that even though William Shakespeare and 8-year-old WS are the same person, and "WS" and "the author of Macbeth" have the same referrent, it's at least not obvious that "8-y.o. WS" and "the author of Macbeth" refer to the same person.
Now, you might just take that as more evidence against the existence of personal identity, but if you're ok with ambiguities like that in our equivalence relation I think you can stretch your mind to accommodate the two Rivers case.
I don't have a specific relation in mind, but, I don't see what the problem is with "you are the same person as your 'ancestors' going back along a timelike path with whom you share the necessary psychological/physical continuity".
The "timelike path" might rule out the specific case of a transporter accident (a feature, not a bug in my opinion, because of the no-cloning thing I mentioned above) but I can imagine like a mitosis sort of duplication that would allow two people to share a common ancestor, so both of them are the same person as that ancestor, but neither is an ancestor of the other, so neither one is the same person as the other. The timelike condition should rule out the possibility of two people being the same person as one another at the same time, which seems to me the most undesirable feature of expanding the notion of "same person" too much--at least, it should do so in sufficiently nice spacetimes.
Notice this isn't symmetric, since you aren't the same person as your descendants even though they're the same person as you--that's what prevents the sameness with the common ancestor from "flowing forward" and making the duplicates the same as each other.
So this is obviously weird, and not completely consistent with how we think of personal identity in the normal case, but I think it has enough resemblance to the usual case that I could imagine someone arguing that we've just been confused by the fact that everyone to ever live so far has only ever had unique descendants, and so we falsely conflated the backward-chain-of ancestors with the chain as a whole. I wouldn't argue that myself, but I think I'd entertain the idea, at least.
This is a thought-provoking thought experiment. But why assume that psychological continuity depends on language? Why not start from subjective experience itself? Subjective experience is real—it’s not merely a linguistic construction. It’s the most immediate reality we have. And it’s physically real too, in the sense that it arises from whatever physical processes generate consciousness.
Now imagine running this experiment on a non-linguistic but subjectively aware organism—say, a frog. If the frog’s mind were duplicated, both resulting frog-minds would likely experience uninterrupted continuity, as if nothing unusual had occurred.
Coming back to the title of your essay—“What If You Were Duplicated by a Transporter Malfunction? Or: Why You Still Don’t Exist!”—your conclusion seems to rest on the idea that neither of the two post-duplication individuals can claim to be the original. But why would that be a requirement?
This reasoning seems to exclude time as a relevant factor. Before the duplication, there was only one me—the original. After the event, there are now two of me. And each one experiences continuity of mind with that original, even if their subjective trajectories begin to diverge from that moment onward.
Sure, their experiences of self will evolve in different directions—but that doesn’t mean they wouldn’t exist. The fact that the self is dynamic doesn’t make it illusory or nonexistent. In other words, this is not specific to being someone. So, this leads me to another experiment. What if a rock was duplicated in the same way. Would you also conclude that it didn't exist?
Hey, thanks for the comment. I'll address a few claims separately. First, you ask why I think that psychological continuity depends on language. The answer here is just that I don't! I say that there are language-independent facts about mental states, in which I include conscious states, as well as about their relations.
One such relation is that some conscious states are continuous with others in the sense you describe. At each moment, there are memories of the preceding few moments as well as anticipations of the next few moments such that no interruptions are perceived. I grant all of that. None of these facts depends on language.
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Second, you ask why two post-fission individuals can't both claim to be the original. Well, the answer here, which I do point out above, is that it doesn't seem to make any sense to say that two distinct individuals that can occupy different points in space, make separate decisions, and so on, are *one and the same person.*
Suppose you have been duplicated. You are at work. Your duplicate is visiting the Eiffel Tower. Your wife calls. She asks, "Hi, where are you?" Is the correct answer that you're at work? Or that you're both at work and at the Eiffel Tower? If you think the former, then you agree that the referent of "you" isn't *two people*!
Let's take it from a different angle. Suppose that you and your duplicate were both at a concert. There are 98 people there, plus you and your duplicate. An employee counts heads. Should he say there are 100 people there? Or 99? If your answer is 100, then you agree that you aren't one and the same person!
Maybe you think this is just because he's not aware of your situation. Suppose you were to go up to him and clarify. You explain that you aren't identical twins. Instead, you're duplicates. Up until just two years ago, you didn't have separate streams of consciousness at all. Do you think now he should change his answer?
Many philosophers would claim that it'd be straightforwardly contradictory to claim that you and your duplicate are one and the same person. Others, would only claim that it's stretching the concept of a person beyond what it can plausibly bear. I'm pretty neutral between the two interpretations, but it's pretty clear that one of the two is correct!
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Third, you ask whether, if a rock were duplicated, I would claim that there's no rock. No, of course not (though see below)! But I would claim that the two rocks aren't *one and the same rock*! That again seems either to be straightforwardly contradiction (two rocks are one rock, and so not two rocks) or else to stretch the concept of *a* rock implausibly.
Now if you were to ask me which one was *the original* rock, *now* I would say *there's no fact about that. And one way I'd support that conclusion is with the quadrilemma presented in this piece. If there were such a fact, there'd be a clear answer to which of the two, if either, is the original rock. But there is no answer. So there's no fact.
As a matter of fact, I would claim that the existence of rocks is language-dependent too. But of course, the loosely defined bundle of physical states we refer to by the term "rock" aren't language-dependent. There's some at least theoretical level of description—subatomic particles? quantum waves functions?—at which they are independent of language.
The same is true of persons. There are physical states that are, at some level of description, independent of language. There are mental states that are, whether identical with those states or supervenient on them or whatever, also independent of language. And there are facts about their relations. But there are no facts about persons over and above those.
If this still sounds odd and if you're interested enough, maybe check out what I say about the Sorites Paradox here: https://substack.com/home/post/p-161991974
Thanks for your reply! You're making a point, if I understand correctly, about the distinction between our descriptions of the world (for example, a “loosely defined bundle of physical states” we refer to with the term rock) and the ‘actual things’—which you describe as “facts” about mental or physical states or their relations. Right?
And then you use the malfunction thought experiment to argue that what we think of as a person is not an actual thing in that second sense, but rather one of those loosely defined bundles of facts. Right? That doesn’t strike me as strange at all—it makes a lot of sense. So much sense, in fact, that it seems to apply not just to persons, but to many other things as well. As I expected, you would argue that the existence of rocks is also language-dependent.
But the malfunction thought experiment does highlight how unsettling this distinction becomes when applied to persons. It raises the question of what, if anything, is essential to being a person. If there are no absolutely necessary facts tied to the description of a person, then we, as persons, don’t exist (in a language-independent way). Right?
Still, your hypothetical examples don’t, to me, clarify this abstract argument very well—assuming I’ve interpreted it correctly. You refer to duplication as “fission” (and also mention split-brain surgery), but it seems to me that what’s really going on in your examples is duplication. And perhaps duplication is better understood as something distinct from fission. For instance, take this example you give:
“Suppose you have been duplicated. You are at work. Your duplicate is visiting the Eiffel Tower. Your wife calls. She asks, ‘Hi, where are you?’ Is the correct answer that you’re at work? Or that you’re both at work and at the Eiffel Tower? If you think the former, then you agree that the referent of ‘you’ isn’t two people!”
Well, distinguishing duplication from fission, I’d say the correct answer depends on who has the phone and answers the call. :-)
I brought up your use of 'you' in the title—second-person—and responded from a first-person perspective.
And from that perspective: after the duplication, I—if you ask me—am either the one at work or the one at the Eiffel Tower. We both exist (we experience our existence first hand), and we were identical up to the moment of duplication. After that, there are two persons, no longer identical. I might be the one at the Eiffel Tower, or I might be the one at work. I might be the one holding the phone, or the other might have it and answer the call.
It seems to me that you are treating duplication of fission a bit ambiguously. The situation where the original is destroyed and then recreated from scratch, one version, two versions, ... is slightly different from when a duplicate is made from the original me and both continue to exist (like in your Eiffel tower example).
One final hypothetical example to illustrate this:
Suppose we had a technology for uploading you into a digital world. Suppose that the procedure is such that, during the upload process, your original body is destroyed—so you experience continuity, but now your consciousness runs digitally instead of in your brain.
But imagine something goes wrong, and the destruction doesn’t occur. Then you’re duplicated. There are now two versions of you, each with their own experience. The original you, whose brain was not destroyed, thinks: “I'm still in my body—what happened?” And the digital version of you thinks: “The transfer worked—I’ve made it into the digital world.”
Then both are informed: “There was a glitch. The original wasn’t destroyed. But a copy was made.” So the one still running on the biological brain now knows: “There’s a digital clone of me.” Meanwhile, the digital clone thinks: “I made it. But oddly enough, there’s still a version of me out there, in a body, continuing to live.”
I imagine that’s quite a disturbing realization for the digital version. But if such technology existed, I think this is what the reality would be: two versions of you, no longer identical from the moment of duplication. Do you agree that this would be the actual outcome?
Reflecting upon our discussion, it seems to me this might in part be a matter of philosophical orientation (which I was unaware about). I’m more drawn to using philosophy as a way to better understand reality, rather than using stylized or hypothetical versions of reality to make abstract philosophical points. That method has its power, of course, but to me it sometimes feels a bit too detached. So perhaps it’s not a disagreement so much as a difference in emphasis or approach.
Hey, the way you summarize my points at the start is right. On the one hand, there’s language, which includes the terms “person,” “self,” “I,” "you,” “Jan,” “Phil,” etc. On the other, there’s reality, which includes physical and mental states in certain relations.
My thesis—which really isn’t mine; I’m just trying to make ideas from Parfit and from Buddhists among other accessible—can be understood as saying that, in reality, there’s nothing that provides a necessary and sufficient condition for the application of those terms.
Now regarding the distinction between fission and duplication: As per the definitions I give, “fission” in the literature refers to any case where two continuants have an equal claim to being the original person. This is true of some of the split brain cases discussed in the literature.
More importantly here, it’s also true of duplication as I’ve described it. That is, a transporter breaks down your original body, transmits the information about your cells to a different location, and then creates two new bodies with all the same psychological states.
It is not true of of cases of duplication where a copy is made of someone, as e.g., in The Prestige. In that case, one of the two continuants clearly is the original person: The one who was in the original person’s place at the moment of duplication! Those aren’t what I’m talking about.
I’ll also use this opportunity to point out that I completely spaced when I discussed your example of the rock. If a rock is duplicated in the way described, i.e., it’s broken down, destroyed, and a perfect copy is created, then the answer is very clear: Neither of the two rocks is the original rock.
Why? Well, this is new matter. And the expression “this rock” refers to nothing else than matter in a certain configuration. Concerns about necessary and sufficient conditions for how much of the same matter there needs to be don’t even apply here, since there’s none of the same matter!
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Now regarding the case where you’re at work and your duplicate is at the Eiffel Tower: We’re discussing the referents of terms like “person,” "self,” “I,” “you,” “Jan,” “Phil,” and so on. These words are used to refer to what we take to be individual persons who we take to be identical across time.
There’s just one such individual person in the world that I pick out when I ask “Where’s Jan?” You were claiming that you and your duplicate (again, in the sense specified) are one and the same person. I was just pointing out that this would commit you to a very odd metaphysical claim.
That metaphysical claim is that this one individual person that is you is at once at work and visiting the Eiffel Tower. If “you” refers to one person and you’re claiming that both continuants are that person, then you’re committed to saying this! Your move of trying to distinguish the person being spoken to from the duplicate just seems to amount to a concession that these are two different people.
Regarding the upload case you describe, it’s is in many ways similar to the first Teletransportation case Parfit considers in Reasons and Persons. But in this case there very clearly is an answer to the question “Where is the original person?” It’s the non-uploaded physical being.
Why? Well, this just isn’t a case of fission. One of the continuants very clearly has more claim to being the original than the other. Of course, in my view, this is just a linguistic convention to refer to physical and mental states in certain causal relations.
But even if there’s no clear set of necessary and sufficient conditions for applying that convention, here there’s really no ambiguity about whether the non-uploaded physical being is the original. It clearly does still fall under our concept of what it is to be one and the same person.
But suppose that I successfully uploaded my mind and destroyed my body. Is the uploaded mind me? That is, did I survive? Or did I die? My answer is: There’s no answer to this question. The fact is that there’s now a pattern of mental states very much like mine. There are no further facts here.
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I guess I’ll just quickly comment on what you say at the end. I certainly see the task of philosophy as coming to better understand reality! And I think that these kinds of thought experiments show us one of the most important things we can learn about reality.
That thing is that there are no persons there independently of language. We can generalize this to say that there are no composite entities of any kind independently of language. These are some of the central claims about reality of certain versions of Buddhism: There is no self, everything is empty of essence.
Why is this so important? Well, I think this thesis has immense practical implications for ethics. I think it also has radical implications for how we understand our own death. Buddhists have drawn out some of these implications for millennia. More recently, Parfit and those he influenced have too.
My view is actually more radical than Parfit’s in this regard. I’m hoping to lead up to a piece on why I think this reductionist account of personal identity entails that death cannot be bad for us. I’m currently on a leave of absence and it’s not entirely clear to me whether I’m going to finish my PhD, but if I do, it’ll be on that!
I see that your duplication scenario is meant to show that “Phil” “I” or “Jan” cannot refer to a single unique entity if two perfect copies exist.
But I’d like to clarify my comment once more. You write: “You were claiming that you and your duplicate (again, in the sense specified) are one and the same person. I was just pointing out that this would commit you to a very odd metaphysical claim.“
Actually I never claimed that my duplicate and I remain one and the same person after the duplication. My position is precisely the opposite. Up to the moment of duplication (t₀) there is a single individual; from t₀ onward there are two—call them Phil‑A and Phil‑B—each with its own causal and experiential continuity. Personal identity is therefore indexed to temporal segments: continuous until the split, then branching. Your critique seems to assume that “identity across time” is an all‑or‑nothing affair, but splitting scenarios show we must assess identity relative to each time‑slice. That one name referred to a single person before t₀ does not obligate us to force both post‑t₀ continuants under the same reference.
Best of luck with further developing your ideas — in a PhD or otherwise.
Hi, loved this post super though provoking! I wanted to ask about the assumption you make early on that psychological continuity is enough for survival, and so we can treat transporters as a form of travel rather than death. What if that assumption turns out to be wrong? Given that we still don't know how subjective experience arises from physical processes is it possible?
Hey, thanks for the kind words! Well, ultimately, my claim is that the assumption doesn't matter. I start off assuming that there are indeed language-independent facts about personal identity and taking for granted that they're facts about psychological continuity, but then by the end of the piece, I claim that there are no such facts!
Suppose I use the transporter. It's a fact that the person who materializes is psychologically continuous with the one who dematerialized. It's a fact that his body is made up of cells that are qualitatively just like those that dematerialized and in causal relations that are identical. It's also a fact that those cells aren't the same ones that dematerialized.
Now is this person me? My claim is that any answer is a linguistic decision. We can say the resulting person is me and that I have a different body, or we can say that he isn't me but that he is psychological continuous with me. But those are just two ways of describing the same thing. There's no fact about which is correct.
Now the worry you seem to be raising near the end seems to be a different one. You seem to be saying something like: How do we know that the resulting being would have mental states continuous with mine given that we don't know the precise nature of the link between the physical brain and subjective conscious experience?
Well, I think we know enough to be at least fairly certain that two identical brains would produce identical mental states, including subjective states. But beyond that, if the person who materializes talks like me, remembers things that happened to me, has my habits, and so on, we can pretty safely assume he also has the accompanying subjective states!
we can safely assume the opposite too, since this is can also be shown to be a decision , not a matter of fact, by similar thought experiments
I think something that's interesting is that the only physically plausible mechanism we know of for a transporter, quantum teleportation, necessarily destroys the original version in the process of teleportation; an accidental duplication would violate the no-cloning theorem.
I think this provides a hint that maybe there actually is something important about physical continuity in thinking about personal identity.
But even putting that aside, I still don't think you're obliged to take duplication as proving that personal identity doesn't exist; it just proves that it's non-transitive (which, I concede is still pretty weird!)
I don't see why you can't just say, me before duplication is the same as each of the two duplicates, but they're not the same as each other. That is, there are two distinct people who are each the original Riker. The original Riker used to be one person, and now he's two different people, just like (okay, fine, not just like, it's obviously way weirder) how the original Riker used to be a child but is now an adult.
But isn't identity a transitive relation by definition?
If the referent of "William Shakespeare" = the referent of "The Author of Macbeth" and the referent of "The Author of Macbeth" = the referent of "The Bard of Avon," then the referent of "William Shakespeare" the referent of "The Bard of Avon," no?
I just don't understand what what you're suggesting would mean! What exactly is this relation that you're proposing?
Well, we already know there are problems with the above in counterfactual reasoning: William Shakespeare=The author of Macbeth doesn't mean that you can replace one with the other in any sentence and have it be true.
And we already face the same issue with personal identity at different points in time: I think most people agree that even though William Shakespeare and 8-year-old WS are the same person, and "WS" and "the author of Macbeth" have the same referrent, it's at least not obvious that "8-y.o. WS" and "the author of Macbeth" refer to the same person.
Now, you might just take that as more evidence against the existence of personal identity, but if you're ok with ambiguities like that in our equivalence relation I think you can stretch your mind to accommodate the two Rivers case.
I don't have a specific relation in mind, but, I don't see what the problem is with "you are the same person as your 'ancestors' going back along a timelike path with whom you share the necessary psychological/physical continuity".
The "timelike path" might rule out the specific case of a transporter accident (a feature, not a bug in my opinion, because of the no-cloning thing I mentioned above) but I can imagine like a mitosis sort of duplication that would allow two people to share a common ancestor, so both of them are the same person as that ancestor, but neither is an ancestor of the other, so neither one is the same person as the other. The timelike condition should rule out the possibility of two people being the same person as one another at the same time, which seems to me the most undesirable feature of expanding the notion of "same person" too much--at least, it should do so in sufficiently nice spacetimes.
Notice this isn't symmetric, since you aren't the same person as your descendants even though they're the same person as you--that's what prevents the sameness with the common ancestor from "flowing forward" and making the duplicates the same as each other.
So this is obviously weird, and not completely consistent with how we think of personal identity in the normal case, but I think it has enough resemblance to the usual case that I could imagine someone arguing that we've just been confused by the fact that everyone to ever live so far has only ever had unique descendants, and so we falsely conflated the backward-chain-of ancestors with the chain as a whole. I wouldn't argue that myself, but I think I'd entertain the idea, at least.