dereta parboIn this discussion over at Edge, Joshua Knobe presents some recent findings of experimental philosophy on the problem of personal identity. Experimental philosophy, which sounds oxymoronic,  is the new and trendy (if it still is?) fashion for philosophising rooted in actual experiments, often of a psychological nature.  The examples I’ve read have all been perfectly acceptable and useful – and why shouldn’t they be? No one ever said philosophy couldn’t be inspired by science, or draw on science. In this case, though, I was not altogether convinced.

After a few words about the basic idea of experimental philosophy, Knobe introduces a couple of examples of interesting problems with personal identity (as he says, it is one of the longer-running discussions in philosophy of mind, with a much older pedigree than discussions of consciousness). His first example is borrowed from Derek Parfit:

Imagine that Derek Parfit is being gradually transformed molecule by molecule into Greta Garbo. At the beginning of this whole process there’s Derek Parfit, then at the end of the whole process it’s really clear that Derek Parfit no longer exists. Derek Parfit is gone. Now there’s Greta Garbo. Now, the key question is this:  At what point along this transformation did the change take place? When did Derek cease to exist and when did Greta come to exist? If you just have to reflect on this question for a while, immediately it becomes clear that there couldn’t be some single point — there couldn’t be a single second, say – in which Derek stops existing and Greta starts existing. What you’re seeing is some kind of gradual process where, as this person becomes more and more and more different from the Derek that we know now, it becomes less and less right to say that he’s Derek at all and more and more right to say that he is gone and a completely other person has come into existence.

I’m afraid this doesn’t seem a great presentation of the case to me. In the first place, it’s a text-book case of begging the question. The point of the thought-experiment is to convince us that Parfit’s identity has changed, but we’re just baldly told that it has, right from the off. We should be told that Parfit’s body is gradually replaced by Garbo’s (and does Garbo still exist or is she gradually eroded away?), then asked whether we still think it’s Parfit when the process is complete. I submit that, presented like that, it’s far from obvious that Parfit has become Garbo (especially if Garbo is still happily living elsewhere); we would probably be more inclined to say that Parfit is still with us and has simply come to resemble Garbo – resemble her perfectly, granted – but resemblance is not identity.

Second: molecule by molecule? What does that even mean? Are we to suppose that every molecule in Parfit has a direct counterpart in Garbo? If not, how do we choose which ones to replace and where to put them? What is the random replacement of molecules going to do to Parfit’s DNA and neurotransmitters, his neurons, his capillaries and astrocytes? Long before we get to the median sage Parfit is going to be profoundly dead, if not reduced to soup. I know it may seem like bad manners to refuse the terms of a thought experiment; magic is generally OK, but what you can’t do is use the freedom it provides to wave away some serious positions on the subject – and it’s a reasonable position on personal identity to think that functional continuity is of the essence.  ‘Molecule by molecule’ takes it for granted that Parfit’s detailed functional structure is irrelevant to his identity.

In fairness we should probably cut Knobe a bit of slack, since circumstances required a short, live exposition. His general point is that we can think of our younger or older selves as different people. In an experiment where subjects were encouraged to think either that their identities remained constant, or changed over time, the ones encouraged to believe in change were happier about letting a future payment go to charity.

Now at best that tells us how people may think about their personal identity, which isn’t much help philosophically since they might easily be flat wrong. But isn’t it a bit of a rubbish experiment, anyway? People are very obliging; if you tell them to behave in one way and then, as part of the same experiment, give them an opportunity to behave that way, some of them probably will; that gives you no steer about their normal behaviour or beliefs.  There’s plenty of evidence in the form of the massive and prosperous pensions and insurance industries that people normally believe quite strongly in the persistence of their identity.

But on top of that, the results can be explained without appealing to considerations of identity anyway. It might be that people merely think: well, my tastes, preferences and circumstances may be very different in a few years, so no point in trying to guess what I’ll want then without in any way doubting that they will be the same person. Since this is simpler and does not require the additional belief in separate identities, Occam’s Razor tells us we should prefer it.

The second example is in some ways more interesting: the aim is to test whether people think emotional, impulsive behaviour, or the kind that comes from long calm deliberation, is more truly reflective of the self. We might, of course, want to say neither, necessarily. However, it turns out that people do not consistently pick either alternative, but nominate as the truest reflection of the person whichever behaviour they think is most virtuous. People think the true self is whichever part of you is morally good.

That’s interesting; but do people really think that, or is it that kindness towards the person in the example nudges them towards putting the best interpretation possible on their personhood – in what is actually an indeterminate issue? I think the latter is almost certainly the case. Suppose we take the example of a man who when calm (or when gripped by artistic impulses) is a painter and a vegetarian; when he is seized by anger (or when thinking calmly about politics) he becomes a belligerent genocidal racist. Are people going to say that Hitler wasn’t really a bad man, and the Nazism wasn’t the true expression of his real self; it was just those external forces that overcame his better nature? I don’t think so, because no-one wants to be forgiving towards Adolf. But towards an arbitrary person we don’t know the default mode is probably generosity.

I dare say this is all a bit unfair and if I read up the experiments Knobe is describing I should find them much better justified than I suppose; but if we’re going to have experiments they certainly need to be solid.


  1. 1. Jesus says:

    Theseus’s paradox is a thought experiment that raises the question of whether an object which has had all its components replaced remains fundamentally the same object:

  2. 2. Vicente says:

    Yeah, I watched the video on Edge and I thought just the same. From experimental anything I expect examples that if not feasible are at least plausible. First thing to draw from science.

  3. 3. Jesus says:

    “At what precise moment does an individual cease to be the person he—and everyone else—believes himself to be? Answer: at the moment when an individual becomes conscious that he has been trapped in a paradox of identity and there is no way out for him as long as he believes himself to be something he is not. Ask any puppet that thinks it is a person.”
    Thomas Ligotti, ‘The Conspiracy Against the Human Race’.

  4. 4. DiscoveredJoys says:

    But… but… we already do this experiment with around 7 billion running at the moment. The DiscoveredJoys of 60 years ago was very different in shape, size, cognitive ability, molecular makeup, memories, personality, life experience, distribution of body hair, teeth and eyesight than the present DiscoveredJoys. I remember me being me, other humans think I have a continuous identity, but when I think really carefully about it the DiscoveredJoys-60 was a different human being, with different attitudes.

    The thought experiment is only worth doing if the change is ‘rapid’, otherwise it is a trivial experiment that tells us nothing. How about when does a caterpillar change into a butterfly?

  5. 5. Jennifer says:

    The idea of the transitivity of self is particularly important when considering watching a person degrade from their actual “self” to the loss of self that comes along with dementia and Alzheimer’s Disease. People that watch their loved ones disappearing and feel like they no longer know a person, understand that the concept of self change is not necessarily one of extremes in philosophical experimentation, but a very real world concept. It doesn’t occur as a molecule by molecule change, but the end result is very similar both to the person who is conscious of slowly losing a self identity (when they can express it, as an artist with AD did in a series of self portraits, according to a former mentor of mine) as well as to the loved ones.

  6. 6. Philosopher Eric says:

    It’s quite a coincidence that only a few hours after I mention Derick Parfit (not that I spelled him right), that you would bring up a scenario where he turns into Greta Garbo. But I will now put all thoughts of collusion aside. Just as Philosophy has not yet entered the realm of science, you Peter have not yet opened up my theory. Though I am indeed working to improve these circumstances, you’ve also given me the opportunity to expand upon my last discussion.

    They said that Derek has somehow changed into Greta. Whether molecule by molecule or anything else, your task is then to tell us exactly where this conversion takes place. Please do not tell us that the presented question is not valid by means of “begging the question” or anything else. Just give us your theory or get out of the way.

    I do indeed have an answer.

    As mentioned last time, I theorize “instantaneous self” which is based upon each moment of experienced sensation. Thus Derick did not have one change, but rather the infinite number of changes — just as you and I are having right now. Furthermore there are essentially just two things which practically hold them together, or “memory of the past,” and “anticipation of the future.” But I must warn you to be careful when you do indeed open my theory Peter. In all your years in this business, nothing has ever “really made sense.” But what would you do, if something finally did?

    Hello Jennifer! It’s not just your name which suggests that you’re from the fairer sex, but your caring observation — not much of this from us dudes/blokes. Perhaps you make your living as a Psychologist? Regardless I do hope that you will consider the theory provided here under my name. From my model there are three varieties of input to the conscious mind, or “sensations,” “senses,” and “memory.” Without this third input, which I define as “past consciousness that remains,” the conscious mind is theorized to be “functionally useless.”

  7. 7. Jorge says:

    Jennifer, you posted
    >It doesn’t occur as a molecule by molecule change

    Ah, well, doesn’t it?

    One beta-amyloid plaque here, one tau tangle there…

    Not that I’m denying there’s a threshold below which the nervous system can cope, but it’s molecule by molecule that one’s identity is disintegrated. (And yes, I know that the exact pathophysiological process is still debated, but it seems highly likely at this point that the main culprit will be amyloid-related)

  8. 8. Philosopher Eric says:

    Jorge that was a prime example of our “insensitive, dorky, dudeness,” so thanks for that one!

  9. 9. Jennifer says:

    Jorge, agreed that’s a change in brain composition. It just doesn’t change a person from an 85 year old man into a young blonde woman – meaning, to clarify, every molecule in the body based on the entirety of DNA sequencing.

  10. 10. Philosopher Eric says:

    Sorry for the disturbance earlier — I shall try to behave myself in the future. But can we now agree that it does not matter how this transformation occurs? Whether by molecules, or cells, or by the very hand of God, we are given that Derick turns into Greta. Therefore by means of “self theory,” we must decide where this happens. But the authors present no such theory, Peter presents no such theory, and as I see it there is only one clear theory shown on the comment board so far. I do not mean to monopolize this discussion, and I regret that I may have stepped on some toes. Nasty business this. But if anyone is up for some philosophy, I’d love to answer questions regarding my own theory, and I am also willing to consider the theory of others.

    To be clear, my theory is that it’s most productive to view “self” as “sensations,” such as pain, hope, love, heat, hatred, and do on. So I define self as a “good/bad,” or “punishment/reward” idea. Self is considered instantaneous in a technical sense, simply because we do not presently experience past and future sensations (by definition). But when the magnitude of positive/negative sensations are compiled over a given period of time, this will be what existence is “worth” to a given conscious entity, whether this is generally horrible or wonderful. Furthermore the value of any such society is also defined by compiling it’s associated experienced sensations.

  11. 11. Katharina says:

    agreed, it sounds like a poorly thought (out) experiment. would, for instance, the cells/molecules (as physical matter) have a physical history? (of that change at least? or of being somewhere else i.e. in/of greta before?) identity to me seems to be essentially (re)produced through a continuously collated, (re)enacted history of existence, and since no two things (fruit bats, atoms, neutrons, kaons, whatever) can have identical (simultaneous) experience -unless they are one thing, and therefore not two of the same thing- then everything is unique, the fact of which forms the basis of its identity and its reality.

    and are we not constantly updating, reworking, reaffirming, reproducing, denying, accepting, losing our identities all of which creates yet new striae to further enact and reflect on?

    to me it seems that the experiment is let down by its failure acknowledge time i.e. cause and effect as producing a history which collectively forms and transforms (an) identity. (can thought experiments just do away with time? isn’t that a little too easy? how about at least positing that time isn’t linear and could therefore produce repetitive loops (as in milan kundera’s ‘unbearable lightness of being’) which would at least give us something to think about in terms of making identity replicable and -by not too large a theoretical leap- replaceable?).

    the experiment must surely conclude that derek is no longer derek or greta: (s)he is (at best) greta who was once derek – which is not the same as being just greta or just derek. (incidentally i think that gender theory would cast some interesting ideas on this argument)

    as with dementia/alzheimer’s, there are many extreme changes (or perceived “losses”) of identity occurring in the everyday (when we undergo trauma, or a “formative” experience for example) consider: “i’m not the man (sic) i used to be” or: “the experience changed me as a person” etc. all of which leads me to believe that derek started to begin to be someone that used to be who he was at the moment the first molecule changed -but just as he was ever-so-slightly someone else before that moment, and so on. i would suggest that it’s dangerous to think of identity in terms of being static or homogenous but something that is immanently in flux; to assume that derek is even the same person from one moment to the next (whether “becoming” someone else in a thought experiment or not) is very reductive and risks slipping into a story of the boiling frog.

    this all seems to strike a chord with eric’s ‘instantaneous self’ -or may well be just that- i’m trying to work it out. eric, when you say “sensations” do you mean also the embodiment of those sensations (as they occurred in the past) or is it whatever is happening presently? you said memory and anticipation “hold them together” – what do you mean by this? that memory and anticipation produce identity through their mediation of sensations in the present?

    future identity is an intriguing concept too – would being all parts derek and no parts yet-greta be constitutive of derek’s identity before the experiment started? and would he therefore have become a “different person” the moment the experiment was conceived? also interesting is the physicality of memory -as brain cells- and when these atrophy as mentioned by jorge.

  12. 12. Philosopher Eric says:

    Along with your other inquiries, Katharina, thank you for asking about my own ideas. I’ve been developing them for such a long time that it all seems quite simple to me, though careful explanations are indeed required. The most I might accomplish here is to spark an interest in you and others to evaluate my manuscript, which is under 60 typed pages and should be accessable through the site which comes up under my name. But to be brief:

    Ch1. Apparently existence can be “significant” to us, or good/bad. We effectively presume that evolution found it useful to engineer the human this way, and perhaps the fly, and perhaps not the fungus, and certainly not bacteria. I name this significance dynamic “self.” Ch2. So then how do we more specifically define this? Apparently we can take a great list of that which seems positive and negative to us, and then figure out the common trait that they all share. Of course different people will indeed come up with different answers, though I find “sensations” to be common to them all, such as curiosity, remorse, fun, thirst, boredom, and so on.

    Chapters 3 and 4 are auxiliary, presenting speculation as to why this may have evolved, as well as the nature of definition itself. In chapter 5 many of the issues raised above are considered however. No… this self does not include past sensations. Observe however that memory of the past does indeed bring us present sensations, and thus imparts continuity with the past. But how then might a present self, be encouraged/forced to deal with the future? This is accomplished through sensations of “hope” (reward), as well as “worry” (punishment). Observe the negative effects of both “hopelessness,” as well as “worrylessness.”

    Ch6. I define mind as that which “processes information” (leaving the rest of reality to be “mechanical”). Ch7. I needed a term to represent “non-conscious mind,” and for cleanliness I used this one rather than Freud’s old “unconscious” term. Ch8. For “input” to the conscious mind there are sensations (self), senses (which generally bring sensations as well), and memory (defined as “past consciousness that remains”). The conscious processor is entitled “thought,” and it also has input and output characteristics. The only conscious “pure output” that I’ve found is termed “muscle operation.” The remaining chapters address varieties of sensation that I find interesting (empathy and theory of mind), as well as social dynamics and the highly repugnant ways in which my theory may indeed be interpreted.

    At minimum I hope to demonstrate how flawed many areas of science must be today given that no such answers have yet been found — though perhaps much more.

  13. 13. Philosopher Eric says:

    Peter has given us a great topic here, and I suppose that I am to blame for diminished participation. So I do now expect some to ask, “Who does this guy think he is?”

    Imagine (as an accomplished physics student) taking your knowledge back to a period before Newton. You might then be proud of your understandings and seek to demonstrate how to solve various physical questions to those in need of such answers. While I haven’t done any such time traveling, this is indeed the position which I perceive myself to be in today. So once I concluded that my theory was ready, and saw Peter presenting supposedly impossible questions that seemed quite answerable to me, this was a natural attraction. But I am only a sheltered theorist… I don’t really know how to get my ideas out. And what exactly is this pool of water which I now cast my line into? But then I perceived a newly minted PhD, as well as her former mentor — world scientists with real world problems to solve. This is the audience that I truly seek!

    I doubt you’ve heard the following scenario: “We’ve got some major problems here, so our best philosophers must get on them right away!” Nevertheless, Psychologists, Psychiatrists, Sociologists, and so on, are indeed commissioned to solve such problems every day. Unfortunately, in my opinion, they do not yet have basic theory from which to effectively do their work. To me they are essentially engineers before the time of Newton.

    As you know I seek to have Peter evaluate my own theory, just as he does with various established thinkers. And perhaps he will indeed do this for me some day. But if so, will it essentially go as his other critiques have? We should certainly expect this of course. But here the nature of his dismissal is something that I’d be quite curious about. Can he demonstrate that he does indeed comprehend my theory? Can he present valid counter arguments? Yes I am most curious about how this would go.

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