Wednesday, July 14, 2010

Personal Identity Review

Here I want to motivate and defend two Parfitian theses. The first is anti-haecceitism or 'reductionism' about identity: the qualitative facts exhaust the facts, and in particular, there remains no "further fact" about the identities of things. We could give a complete description of the world without using identity-talk at all. Talk of identity over time is just a convenient shorthand for talking about various kinds of continuity and counterfactual dependence. The second thesis, then, is that when it comes to the persistence or identity of persons across time, the kind of continuity worth caring about is psychological continuity.

I. Anti-Haecceitism.

Consider a world (w1) containing two qualitatively identical soccer balls. Now consider the distinct possibility (w2) that just one such ball ever existed. Once we specify all the qualitative details -- e.g. the size, shape, and mass of the ball -- is there any further matter that we remain ignorant of? In particular, could we sensibly wonder about the identity of the ball, e.g. whether it is "really" either of the two balls that would have existed in possibility w1? Presumably not. It is difficult to comprehend what in the world a mere difference of identity would consist in. One proposal is that there are 'haecceities' -- properties such as being ball_1 or being ball_2, which float free from the qualitative natures of the objects. But then it is hard to see what in this theory precludes such seemingly nonsensical behaviour as objects switching haecceities from one moment to the next -- or even instantiating multiple such properties at once.

What's more, once we shift our attention from trans-world to trans-time identity, we can construct fission cases that seem to pretty conclusively establish that identity across time is not intrinsic. In short: Fred would survive if just his left brain hemisphere were successfully transplanted into a new body ('Lefty'), and likewise if just his right hemisphere were transplanted into a different body ('Righty'); but if both Lefty and Righty survive, then - since they are distinct from each other - they cannot both be identical to Fred. Hence, whether Fred (at time t1) and Lefty (at t2) are the "same person" does not depend just on the intrinsic properties of the respective person-stages; it also depends on whether there is any other stage (e.g. Righty) with an equal or better claim to being Fred's closest continuant at t2.

So the identity facts are not "built into" the objects themselves. They are better understood as merely conventional: we may say that "Lefty is Fred", when Lefty is a sufficiently close continuant of Fred and there are no real competitors for the title; but we aren't tracking any "deep further fact" about the world when we do so. If Righty exists as well, then we may refrain from bestowing the title of '[closest continuant of] Fred' on either of the equally-eligible candidates, but of course Lefty himself is not any different for lacking the title. It is merely a difference in how we talk, not a difference that Lefty need regard as having any real significance.

This deflationary, reductionist view may also be supported by examples like the Ship of Theseus, or the following example (adapted from Parfit): Suppose Jim has fond memories of a now-defunct social club that he founded as a youth. He decides to start a similar club, with the same name and membership rules as his old club, but new members. Once we have all these qualitative details about the connections between the two clubs, it'd clearly be vacuous to ask whether or not they are really "the same" club. It's not as though there are two open possibilities here. We know what the situation is; the only remaining question is how we choose to describe it. (See also: 'Arbitrary Persistence'.)

The counter-intuitive step comes when we apply this same reductionist understanding to questions of personal identity. When faced with teletransporter cases and the like, we're inclined to think that there must be some deep further fact about whether the person that emerges on the other side is really the same conscious experiencer as the person who went in, or a mere replica. (I'm tempted to phrase the intuitive worry in terms of whether the same 'stream of consciousness' continues on, or whether a new 'stream' begins where the last one left off. But that can't be quite right: we ordinarily think that disconnected streams of consciousness -- e.g. before and after sleeping -- can be experienced by the same enduring person or 'subject of experiences'.)

This way of thinking seems endemic to our self-perception: we don't just think that there will exist a future stage, related to our present stage in various ways, who will experience such-and-such. We anticipate experiencing that future ourselves. And so puzzle cases like teletransporters and fission cases strike us as puzzling precisely because we assume that there is an important first-personal difference between whether those futures are experienced by us or instead by other minds that merely happen to be very similar to ours. Those seem like distinct possibilities, in a way that alternative answers about the identities of inanimate objects (like the Ship of Theseus, or Jim's social club) do not.

I feel the force of this intuition, but I think we should ultimately reject it as a mere psychological confusion. The previously mentioned theoretical reasons for rejecting haecceitism in general strike me as extremely powerful, and they would seem to apply no less strongly when it comes to the identities of mental entities. (See also Velleman on the illusion of endurance.) But I'd be interested to hear how others respond to this dilemma.

[Aside: Parfit himself seems to regard reductionism as merely contingently true. I'm inclined to the stronger view that non-reductionism about identity isn't even a coherent possibility.]

II. Psychological Continuity

Given that there are no "deep further facts" about identity for our concerns to track, what should we care about in survival? As Parfit argues, one thing that fission cases show is that we shouldn't care about conventional identity ascriptions, since identity depends on extrinsic facts, whereas Fred's attitude towards Lefty should depend only on their intrinsic features and relations. Since Fred would regard himself as 'surviving' if just Lefty (or Righty) survived, he should regard the outcome where both Lefty and Righty survive as a kind of "double survival", even if we can't strictly speaking identify him with either survivor. [See also 'Fissioning in Prospect and Retrospect', where I argue that fissioning followed by the painless death of Righty is about as good as ordinary survival.]

Okay, so we should care about some (multiply instantiable) relation of similarity/continuity. But which one? The possibility of surviving as a 'brain in a vat' seems to rule out considering one's body as essential. So the serious contenders seem to be:
(i) the physical continuity of your particular brain (whatever general psychological qualities it might give rise to), or else...
(ii) the continuity of your general psychological qualities (memories, values, personality, etc.), whatever physical entity these might be based in.

The first option might seem intuitive to the extent that one retains the Cartesian picture of an enduring self. But once we accept reductionism, the second option seems to make a lot more sense. I care about my memories, values, etc., and I want to see my intentions carried out and my projects brought to fruition. It doesn't make any difference to me whether the Richard-like mind that takes care of my future business is a mind that's grounded in a brain physically continuous with my current brain, or whether future-Richard's brain is instead reconstructed from all new atoms on the other end of a teletransporter 'journey'. I don't necessarily have any argument to offer to someone who finds that they continue to intrinsically care about the persistence of their particular brain even after accepting reductionism; such a response just seems inexplicable to me, so I assume that responses favouring the psychological view will be much more common.

P.S. One might not even need to accept reductionism in order to be drawn to the view that psychological continuity is what matters in survival. Locke pointed out that however seriously we entertain the hypothesis that we share a bare "soul" with Hector of Troy, so long as we are not thereby supposed to inherit any of his memories or other psychological qualities, we find ourselves unable to really consider ourselves the same person as Hector in any sense that matters. On the other hand, if a Cobbler inherits the memories and personality of a long-dead Prince (completely overriding any trace of the Cobbler's mind), for everyone involved it is as if the Cobbler has been killed and the Prince resurrected in his place -- no matter whether there has been a change of haecceity (or identity of the immortal "soul" that we imagine to inhabit the body).


  1. Richard, I'm not sure I understand what you mean when you say that fission cases do not involve two distinct possibilities. If I step into a teleporter alone but two copies of me appear on the other end, one of which is hideously deformed, I think there is a real question as to whether I have become hideously deformed or I have just acquired a hideously deformed twin.

    In terms of a counterfactual scenario in which I have a twin, it seems like we can be Anti-Haecceitists and say that there is only one world representing two possibilities, maybe according to different counterpart relations, in which I am either twin A or twin B.

    But if it's an indicative possibility that we're talking about, would we say that there is one scenario that represents two possibilities, or do you mean to say that that there is only an illusion of two possibilities?

  2. Richard would you mind if I ask some general questions to flesh out your stance? The perspective I use is somewhat different so I haven't had the opporunity to go into this in such fine detail.

  3. Simon - sure, questions are always welcome!

    Soluman - I had in mind the strong claim that it's an illusion to think that there are two possibilities here. Once we're given the qualitative facts (incl. the various relations of physical and psychological continuity between your present stage and the two future stages) we know all that there is to know about the situation. The remaining question is semantic: how to apply our 'identity' talk to the case.

    I'm a bit puzzled by the proposal that counterpart relations might help the anti-haecceitist preserve our "further fact" intuitions. Isn't the selection of one counterpart relation over another largely conventional (and depending on conversational context, salient dimensions of similarity, etc.)? So long as there's no "one true" counterpart relation, the resulting view looks pretty deflationary to me. We can appeal to these various relations to serve as truthmakers for ordinary claims like "I could have been deformed"; but it's important to note that the truth of this modal claim doesn't really consist in anything more than the qualitative possibility of a deformed guy who is similar to me in various ways. There's no further sense in which he "really is" (or isn't) me.

  4. Well, I'm not sure that counterpart relations are helpful. In a counterfactual scenario where I am one of two twins, one of which is deformed, I don't say it is a world where am both deformed and not deformed. I can stipulate which twin I am at that world via a counterpart relation. When I talk about different counterfactual possibilities, I feel like I'm talking about pairs of worlds and counterpart relations.

    But if its an indicative possibility that we're talking about, then I feel like there's a problem. What if I'm fissioned in the actual world? The indicative possibility is already centered, so doesn't that make two different scenarios? One centered on the normal and one centered on the deformed output of the telepod? So that's two different epistemic possibilities, at least.

    Also, I'm a little confused as to what you think it would be like, phenomenally, to be fissioned. Isn't personal identity linked to qualia? If some cosmic shift at the actual world causes my qualia to be put out like a light, that will be the day that "I" cease to exist (although I could have been a zombie under some counterpart relation, I can't actually be a zombie). If I am fissioned, it seems like I will either cease to have experiences, have one, or maybe have two simultaneous streams of qualia. You're saying that those are all the same possibility?

  5. I guess I'm assuming that qualia are all anchored to particular moments of time: not really 'streams' at all, in an important sense. So there's something it's like to be Fred at t1, and something it's like to be Fred-Lefty at t2, and a very similar something that it's like to be Fred-Righty at t2. And that's it. There's not any further fact about what it's like for Fred-of-t1 at t2.

    In particular: It's not as though Fred-of-t1 is going to end up being 'centered' on one or other of Lefty or Righty. He can imagine things from either perspective, but both perspectives will end up being realized, and neither is literally 'him' in any deep, further sense.

    It might still be appropriate from him to 'anticipate' both futures, insofar as each future is psychologically continuous with his present self in the way that (I think) matters morally. But if reductionism is right, we shouldn't think that the appropriateness of this imaginative projection reflects any further metaphysical fact that may or may not obtain, over and above the settled qualitative facts.

  6. While I acknowledge that one prefers to persist with one's own psychological continuity I've always thought that it necessarily went with some sort of additional persistence relationship. Even so I would also be quite happy to lose my memories and personality, when given a choice between that and dying.

    Would you be happy to use destructive teleportation when it appears to me just to make a copy of you? To me it is no more ‘numerical’ you than a teleportation that leaves you on Earth but with copy on Mars.

    I do see Parfit’s point but I just don’t take it where he does. After all for me if it isn’t me, I don’t give a damn who has my thoughts and desires, but on the flip side if I were to have immortality through being cryogenically frozen but never being able to ‘wake up’ there is no point to that either.

    So his argument is enlightening but I think it still a dead end as far as helping finding a coherent and consistent personal identity/ontological identity account.

    I flatter myself to think my work will do that.:)

  7. Yeah, it's interesting. One way to characterize reductionism about identity is as the thesis that ordinary survival is relevantly similar to being replaced by a new copy every passing moment (there happens to be more physical continuity in the ordinary case, but no enduring 'self' of the sort we typically imagine).

    But now there are two ways to respond to this equivalence: we might 'upgrade' our opinion of replication, or we might 'downgrade' our opinion of ordinary survival. I'm inclined towards the former, but I could see how you might go the latter route instead. (Parfit sometimes suggests things along these lines, e.g. about how the reductionist view helps to break down the mental barriers we erect between 'ourselves' and 'others', instead leading one to adopt a more impartial perspective.)

  8. I'll have to go a read over some of your related posts but its 3.07 in the morning now and my brain is starting to slow.

    But on the face of it I'd agree there is no enduring 'self', but I don't equate the 'self' as our numerical identity as an indivudual. Rather my account has much in common with the biological continuity as a bounded constituted entity -replacing parts and matter notwithstanding- but I found a way to get around the common intuitions of fission and the brain swap. Apart from other things I don't make the claim that I'm an animal, body or organism ontologically but another class of things entirely. :)

    BTW I always like to know frrom people who think about this stuff, do you think animals have psychological continuity or that animals can think or be persons?

  9. Richard, so you don't think there are any identity problems with people becoming zombies? Suppose I'm uploaded into a functional silicon duplicate as part of a singularity scenario, and it turns out that functional silicon duplicates don't have qualia. Would you say that this duplicate is still me?

    Would you say that me at t1 has a property (qualia) that me at t2 lacks? Is that different than saying that me at t1 has a property (having a moustache) that me at t2 lacks? I just have a hard time identifying something as myself that is not phenomenally continuous with myself, even if it is psychologically continuous.

  10. Soluman - I agree that the kind of 'psychological continuity' we care about concerns phenomenal mental states, not just the functional kinds. (There's an important sense in which zombies don't really have beliefs and desires at all. See 'zombie rationality'.) That's compatible with reductionism about identity.

    Simon - some animals might have at least a rudimentary sort of personhood, insofar as they think of themselves as temporally-extended beings with projects and concerns for the future. I don't have any firm views on the empirical question. But I expect that most animals merely 'live in the moment' (however well their moment-to-moment instincts might prepare them for the future). See also: 'Can Death Harm Non-Persons?'.

  11. Hi Richard --- a couple of quick thoughts about your stuff at the beginning on the metaphysics of identity. (I'm not sure if any of this is ultimately of relevance to the issue of personal identity.)

    First, soccer balls. I think your discussion leaves a very natural view out of the picture. The view might be called "individualism", namely that at the fundamental level of description the world consists of a domain of objects propertied and related in various ways. On this view, objects---those things that bear properties---are fundamental entities. Now, suppose there are two such things, A and B, and suppose they each have the same qualitative properties (e.g. they are both soccer balls). Then it seems perfectly easy and coherent to describe *two* distinct possibilities in which only one of them ever existed. You object that it's difficult to comprehend what the difference could consist in, but what's wrong with saying this: in one possibility it is just *A* that exists; while in the other it is just *B* that exists!

    Note that in saying this, the individualist is not supposing that each ball has a mysterious "haecceity". You (and most people in the literature too) are thinking of haecceities as mysterious, non-qualitative properties that objects instantiate in addition to their qualitative properties. I agree that properties such as those are bizarre for the reasons you point out and should be banished. But the individualist I'm imagining posits no such thing. Of course, since the individual A is part of her fundamental ontology, she might naturally think that there is such a thing as the property of being identical to A. But this is nothing mysterious: it is simply a complex property consisting of the identity relation and the individual A. In particular, it is not the sort of property that objects could swap from one moment to the next (i.e. A could never have the property of being identical to B!)

    Now, I think that individualism should be rejected, but it's not the wacky "haecceities" view that you attack. Indeed, I think it's probably the view that we all start out with implicitly, and certainly a view that's implicitly presupposed in most contemporary metaphysics.

    Things might be different when it comes to non-fundamental entities. For in that case, since the entity is derivative, the question "in virtue of what is it A rather than B" needs answering, and not just by stipulating that it's A! So when thinking about the sorts of possibilities you mention with the soccer balls, I think a lot depends on whether the entities in question are fundamental or derivative.

    Second: identity across possible worlds is different from identity across times, and lessons in the one case might not carry over straightforwardly to the other. Since your ultimate concern is identity over time, perhaps you don't need to rest anything on the soccer balls case anyway? If you were using it just to break us in slowly, fine; but if you intended it to imply something about identity over time, I'd like to hear more about what you think the connection is between identity across worlds and identity over time.

    Hope you're having a good summer,

  12. Richard so like me you think that the traditional justification that animals don't think via the brain swap thought experiment is flawed? Or that the Thinking Animal problem isn't in fact a problem?

  13. PS I'll go over your harm post but IMO we have interests grounded in ways other than just having desires.

  14. Shamik - thanks, that's helpful.

    I wonder how many of the problems for haecceitism might be inherited by individualism anyhow. For example, doesn't the problem of indiscernibly switching haecceities carry over to the idea that we could have indiscernibly switching individuals? (We start off with A exemplifying some set of qualitative properties at t1, and then at t2 it suddenly [without so much as a puff of smoke] happens to be individual B in that spot exemplifying those very same qualities. I guess individualists might find this less of a bullet to bite, but I must admit I still find it hard to wrap my head around the idea that this is so much as a coherent possibility.

    Still, you're probably right that I'm biting off more than I really need to here. Sticking to the temporal case -- especially if persons are 'derivative' rather than 'fundamental' entities -- reductionism about identity retains an independently appealing view.

  15. Simon - I'm not sure what you're referring to here. Is the idea just that it's brains, rather than the whole organism, that does the thinking? I'm on board with that. (I thought you were previously asking whether non-human animals could be persons in light of their limited cognitive capacities. But I can't imagine what brain-swapping thought experiments could have to do with that question.)

  16. Yeah, individualism comes with its own problems, some of which might resemble those of haecceitism. Though note that the scenario you envisage is physically impossible, so the individualist might diagnose your finding it weird as just being a product of it being physically absurd.

    Also, while I find (what you call) haecceitism barely intelligible---I really struggle to understand what these haecceities could be---individualism seems to me perfectly intelligible and very natural. Since many people object to haecceitism on the grounds that it's barely unintelligible, it's useful to distinguish it from individualism.

  17. Richard yes and no, though I think you should look up the Mereological Fallacy and embodied cognition as well. BTW The ‘Thinking animal problem’ is also called the ‘Too many minds’ or ‘Too many thinkers’ problem. Eric Olson talks a lot about it.

    Again basically the traditional argument goes, because we persist psychological as persons in the brain swap experiment it is inferred we aren’t the animal body or organism that’s left behind. Or put another way by someone like Eric Olson “that no organism could have mental properties” which I also take to mean no organism or non-human animal has psychological continuity. Now if I cannot infer that, it would mean we can say that human organisms /animals don’t think or have psychological continuity, but it is possible for less cognitively sophisticated organisms to have psychological continuity, which would be intuitively strange.

    (I thought you were previously asking whether non-human animals could be persons in light of their limited cognitive capacities. But I can't imagine what brain-swapping thought experiments could have to do with that question.)

    We were, and I was just seeing if you see the forest and not just the trees.

    The tradional psychological vs biogical continuity debate is flawed in its framing; brain swaps don't in fact indicate that animals cannot think or don’t have at least a weak type psychological continuity, because if you swap the brain of dog the memories and cognition also go where the bogs brain goes and yet it also leaves the body/animal/organism behind. So via similar reasoning many animals aren’t animals or organisms via a brain swap. In the articles I characterised these non-person non-human animals as ontologically speaking, ‘personalities’ and not animals/organisms or bodies.

    So the traditional dichotomy between psychological continuity as persons vs. Biological or Animalism continuity doesn’t even get the basics right. We shouldn't even be arguing about psychological continuity vs biogical continuity that includes any animal that has a brain and basic memories/adaptive behaviours, rather it should be psychological continuity as personalities vs biological continuity of simple oragnisms with either very basic or even no brain at all.


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