- Could we outlive, or be outlived by, those human organisms that are so intimately connected with us? Many philosophers think so, and they often tell stories like these: 'If all my psychological features were permanently wiped out, but in a way that left this human organism (the one you point at when you point at me) intact and alive, I should cease to exist and that organism would outlive me. If, on the other hand, you destroyed this organism, but only after removing my cerebrum1 from my head and implanting it into another, I should outlive that organism. For there would still be exactly one person who would be able to remember my life, and whose memories and character were caused in the appropriate way by mine.'
- According to this highly popular view, a person's persistence consists in a relation that is essentially psychological. This relation may need to be restricted in some way: perhaps I persist only if no more than one person can remember my life, or only if that person's memories are connected in a physically continuous way with my experiences. But some relation involving psychological continuity2, they say, is both necessary and sufficient for a person to exist at two different times. Let us call this view the Psychological Approach to personal identity3.
- Arguments for the Psychological Approach based on science-fiction stories are as common as can be. But philosophers have had much less to say about the ontological consequences of that view. I will argue that the Psychological Approach faces ontological difficulties far more serious than its proponents have suspected. The problems arise because that view apparently entails that you and I are not human animals4 – we are not members of the species Homo sapiens. If we can outlive, or be outlived by, 'our' organisms, we cannot be those organisms, for a thing cannot outlive itself. But few friends of the Psychological Approach have thought carefully about what sort of beings we might be, if we are not animals, or about how we are related to those human animals5 that, except in science fiction, so faithfully accompany us throughout our lives. I will argue that there are no satisfactory answers to these questions. Or at any rate I will try to show that the range of possible answers is so problematic that we ought to consider giving up the Psychological Approach.
- Now a few friends of the Psychological Approach have claimed that we are human organisms, avoiding the difficulty I mean to exploit6. They believe that, because of their intelligence7, human animals have a criterion of identity8 radically different from that of most of their evolutionary9 cousins. (I take it that gazelles and goldfish do not persist in virtue of psychological continuity10.)
- Those philosophers believe that I have described the 'oblivion' and 'transplant11' cases incorrectly. Imagine once more that my psychology is destroyed in a way that does not cause death in the ordinary sense (my heartbeat, respiration, and other vital processes continue without interruption). Their view is that this human organism would not outlive me, in that case, but would cease to exist when I do (since I am that organism). The animal that results from the memory-loss, they say, is numerically different from the one that suffers it12.
- They also believe that if my cerebrum13 is transplanted14 into another head, carrying all my psychological features along with it, the living, breathing, but brainless human organism left behind would not be the animal once associated with me. That animal, they say, briefly becomes a naked cerebrum15, a hunk of tissue which is no more a living organism than a freshly severed arm is an organism. It is then implanted into the empty cranial cavity of another living human animal16, at which point it becomes an organism once more by assimilating the vital functions of its 'host'. The animal that receives my cortex presumably ceases to exist at this point, even though its autonomic nervous system continues to work without interruption. So their version of the story calls for at least three human animals17:
- one (me) which has my memories throughout and is not an organism at all during part of the operation;
- a second, which apparently comes into being when my cerebrum18 is separated from the rest of me; and
- a third, which perishes (or at least ceases to be an animal) when I, a naked cerebrum19, am implanted into it20.
- This is a very unnatural way to describe our two cases. Quite aside from what happens to me, the facts about biological continuity at least strongly suggest that in the 'oblivion' case there is just one animal, which can remember things when the story begins and can no longer do so when the curtain fails. (Or, if people are not animals, one animal is first associated with a remembering person and afterwards is associated with no such person.) And in the 'transplant21' case the physiological facts suggest that there are just two human animals22, not three (or four), and that a cerebrum23 is simply transplanted24 from one to the other, much as a kidney might be.
- For these reasons I shall assume that narrowly biological (non-psychological) criteria are both necessary and sufficient for the persistence of human organisms: Thus their criterion of identity25 is not the one specified by the Psychological Approach, and if that Approach is true, you and I are (apparently) not animals. But if we are not human organisms, what sort of beings are we? And how are we related to 'our' human organisms26. I will consider five27 ways in which friends of the Psychological Approach might try to answer these questions.
Printout heavily annotated: requires writing up.
Footnote 6: Unger says that each of us was once a week-old fetus, which at least suggests that we are human animals (op. cit., p.6). And Thomas Nagel, while saying that we are animals, also claims that one survives as long as the seat of one's experiences and one's capacity to reidentify oneself by means of personal memory is preserved ('I could lose everything but my functioning brain and still be me'). This suggests that the continued existence of certain psychological capacities (if not psychological continuity itself) is necessary for us to persist, and thus that our criterion of identity is not narrowly biological. ("Nagel (Thomas) - The View from Nowhere" (1986, pp.40-42.) But 1 may be misreading Nagel.
- Philosophers who accept some version of the Psychological Approach include
- "Grice (H. Paul) - Personal Identity" (1987);
- "Lewis (David) - Survival and Identity" (1983);
- "Locke (John) - Of Identity and Diversity";
- "Noonan (Harold) - Personal Identity" (1989), see esp. p.13;
- "Nozick (Robert) - Philosophical Explanations" (1981, Chapter One: ie. "Nozick (Robert) - Personal Identity Through Time");
- "Parfit (Derek) - Reasons and Persons" (1984);
- "Quinton (Anthony) - The Soul" (1962);
- "Perry (John) - Can the Self Divide?" (1972);
- "Shoemaker (Sydney) - Personal Identity: a Materialist Account" (1984);
- "Unger (Peter) - Identity, Consciousness and Value" (1990); and
- "Wiggins (David) - Identity & Spatio-temporal Continuity" (1967).
- I confess that this list may be contentious. Unger, for example, is at pains to argue against what he calls 'psychologically based' theories of personal identity. But his own view is that some sort of psychological continuity, provided that it is continuously physically realized (and that 'branching' is ruled out), is both necessary and sufficient for us to persist (see p.140). Thus his theory is a version of the Psychological Approach as I have defined it, and my arguments against that approach apply to Unger as well. Even Johnston, after a trenchant critique of views on which personal identity consists solely in psychological continuity, writes,
Rather than see ourselves as minds whose particular embodiments are contingent, we will see ourselves as human beings: that is, beings which necessarily are normally constituted by human organisms, and whose conditions of survival deviate from those of their constituting organisms only because a human being will continue on if his mind continues on... [p.64]
- And Wiggins, who now seems to oppose the Psychological Approach, once wrote,
We are not identical with our bodies... The concept which belongs to physiological science is human organism, human body, or whatever. We can imagine such things being replenished with spare hands, spare kidneys and with spare brains. The repair need not preserve character-continuity or memory-continuity. But if this is the physicalistic way of looking at the individuation of persons then the way of physicalism is wrong. [pp.57f.; see also p.51]
- This clearly implies that we could not survive radical psychological discontinuity.
Footnote 12: Several friends have tried to persuade me that I am not a 'mere' human organism but a 'functioning' organism (or perhaps a 'functioning' brain), where functionality implies retaining certain psychological capacities and a degree of psychological continuity. This is supposed to make it clearer why a person could not become an animal (or a brain) with no capacity for thought. I do not understand their suggestion. Either the 'functioning' organism is identical with the 'non-functioning' organism that results in the 'oblivion' story, or it is not. If so, then I can persist without psychological continuity (though I may cease to be a person or a 'functioning' animal), contrary to the Psychological Approach. If not, then biological continuity is not sufficient for an animal to persist, and their suggestion is of no help at all.
Footnote 13: Why not the entire brain? Transplanting the cerebrum alone gives the psychological 'transfer' effect we want, but leaves intact the autonomic nervous system, based chiefly in the brainstem, which coordinates one's vital functions.
Footnote 20: In fact the story requires a fourth human animal: there must have been a human being whose cerebrum was removed from his skull to make room for mine to be transplanted. That organism must have either ceased to exist, or become a naked cerebrum, depending on what the surgeons did with his brain when they removed it. Of course that organism cannot be identical with the animal into whose skull my cerebrum is transplanted, on the current proposal, for there is no psychological continuity linking them.
Footnote 26: There is a further reason for my view. The existence of fetuses (in particular, human fetuses less than about six months old, which, embryologists tell us, are not yet capable of thought), anencephalics, and coma patients (not to mention the brainless human organisms in the 'transplant' case) shows that psychological continuity cannot be necessary for the persistence of just any human organism, since those human beings manage to persist without it. So if psychological continuity is somehow relevant to our identity, then either different human organisms fall under different criteria of identity, or (more plausibly, if we were once fetuses or could become terminally comatose) the human criterion of identity is a complex disjunction of psychological and biological components – a sort of 'best-candidate' theory. As far as I know, no philosopher has yet proposed a version of the Psychological Approach that can accommodate these cases.
Footnote 27: Note: These are:-
- Dualism – we are minds,
- Nihilism (there are no persons),
- Relative Identity,
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