- Are we people, or are we animals? Surely both, you will say! And I say so too. But most philosophers apparently disagree. They think that our identity through time consists in a relation that is essentially psychological; and that entails that we are not animals.
- Imagine that your cerebrum1 is cut out of your head and implanted into another, and that this produces someone who thinks he is you, has your personality (warts and all), and who can apparently remember just as much of your past as you can now remember. The contemporary philosophical wisdom about this sort of "transplant2" case is that the person who ends up with your cerebrum3 and your memories is you. For he, and he alone, is psychologically continuous with you as you are now; and, for good measure, that continuity is secured by the physically continuous presence of your cerebrum4.
- Now imagine, if you can, that you undergo total oblivion: all of your psychological features and capacities are somehow permanently destroyed, but in a way that does not disrupt your heartbeat, respiration, and other vital functions. Most philosophers think that you could not survive oblivion. For the mewling, puking human being who results from this adventure is not psychologically continuous with you as you are now. In fact he bears no more interesting psychological relation to you than you bear to me.
- The lesson most philosophers draw from stories like these is that some relation that is at least partly psychological is both necessary and sufficient for us to persist from one time to another. Some say overlapping chains of experience-memory, for example. Others say that we are individuated by our mental capacities: one goes where one's mind goes. This difference does not matter here. I shall call this kind of view the Psychological Approach to personal identity.
- If that is the right way to think about these stories, we can draw a second lesson from them as well: that you and I are not animals. Not only are we not essentially animals; we are not living organisms at all, even contingently. For when the surgeons transplant your cerebrum5 from one head to another they do not transfer any animal from one head to another. What they do (according to the Psychological Approach) is transplant6 you from one animal to another. Nor does any animal cease to exist when you lose your memories in the "oblivion" case. The animal in the story simply outlives you. So if the Psychological Approach is true, you and I cannot be animals. For the criterion of identity7 it assigns to us is not one that could apply to animals with human physiology. It is certainly not the criterion that applies to members of the species Homo sapiens.
- But don't we think that we are animals? Isn't it obvious that we are human animals8 if we are material objects at all? If we are material (and I shall assume that we are), and unless we are radically mistaken about the conditions under which an animal can survive, it seems that the Psychological Approach could not be true. Instead we must have a criterion of identity9 appropriate to human animals10: our persistence must consist in some sort of narrowly biological relation. I shall argue that our criterion of identity11, like that of our evolutionary12 cousins, has nothing to do with psychology. This Biological Approach, I claim, is the only view of our identity that is consistent with the fact that we are living beings.
- The Biological Approach has been unjustly neglected in the debate over personal identity. In Harold Noonan's recent book13, considered an authoritative survey of the subject, the Biological Approach is last mentioned on page 5. John Pollock14 dismisses it as "a straw man." The Psychological Approach, on the other hand, is as popular as can be. It has taken its place as the new orthodoxy in the field of personal identity. The editors of the recent anthology15 Self and Identity, to take just one example, include nine philosophical articles on personal identity. Eight of those presume some version of the Psychological Approach; only one, and by far the oldest (a 1970 article by Bernard Williams), opposes16 it. Besides Noonan and Pollock, Mark Johnston, David Lewis, Thomas Nagel, Robert Nozick, Derek Parfit17, John Perry, Anthony Quinton, Sydney Shoemaker, Peter Unger, and David Wiggins are only a few of the eminent figures who have endorsed some version of the Psychological Approach18. Noonan is certainly correct to say that the Biological Approach "has not proved popular with philosophers."
- In the next section I shall argue – if an argument is needed – that you and I are human organisms. In section three I consider the view that human animals19, unlike our evolutionary20 cousins, might be individuated on psychological grounds. Finally I shall argue that only a radically non-psychological approach to personal identity can accommodate the fact that we are living organisms. This is shown by the very thought-experiments21 that figure in arguments for the Psychological Approach.
Footnote 1: 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 13: Footnote 14: See "Pollock (John L.) - How to Build a Person: A Prolegomenon" (1989, p. 30).
Footnote 15: This would seem to be "Kolak (Daniel) & Martin (Raymond), Eds. - Self and Identity: Contemporary Philosophical Issues", but the essays don’t seem to tie up. Maybe I have a different edition – Olson doesn’t give any bibliographical details or even the authors; but, neither of the papers alluded to are in my edition.
Footnote 16: Although Peter Unger's contribution is devoted to what he calls the "physical view" of personal identity, he points out that "even the physical approach is aimed at certain psychological factors, namely, those of core psychology. A person's physical parts and structures are important to her survival only insofar as they continue to support, and to realize, her basic psychological capacities" (p. 195, emphasis original). According to the Biological Approach, on the other hand, psychology is irrelevant to our survival.
- "Johnston (Mark) - Human Beings" (1987, see esp. p. 79)
- "Lewis (David) - Survival and Identity" (1983);
- "Nagel (Thomas) - The View from Nowhere" (1986, pp. 40-43);
- "Nozick (Robert) - Philosophical Explanations" (1981, Chapter One: ie. "Nozick (Robert) - Personal Identity Through Time");
- "Parfit (Derek) - Reasons and Persons" (1984, esp. p. 216);
- "Perry (John) - Can the Self Divide?" (1972);
- "Quinton (Anthony) - The Soul" (1962);
- "Shoemaker (Sydney) & Swinburne (Richard) - Personal Identity" (1984, esp. p. 90);
- "Unger (Peter) - Identity, Consciousness and Value" (1990, esp. pp. 140-141);
- "Wiggins (David) - Identity & Spatio-temporal Continuity" (1967, pp. 48ff., 51, 57).
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