Time and Identity

9 Persons, Animals, and Human Beings

Introduction The position I defend takes psychological continuity as the sole and sufficient criterion of personal identity.1 I here confront the suggestion recently made by a number of authors, including Paul Snowdon (1991), Peter van Inwagen (1990), and Eric Olson (1997, 2002), that any such psychological approach must be mistaken, because in fact the correct account of personal identity is given by the biological approach, according to which we are human beings whose identity over time requires no kind of psychological continuity or connectedness whatsoever. The standard objection to the biological approach is that it conflicts with our intuition that in the transplant case, in which Brown’s brain is transplanted into Robinson’s body, with consequent transfer of psychology, the survivor Brownson is the brain donor Brown. This “transplant intuition ” has been challenged by recent defenders of that approach, particularly Olson, who have also developed additional arguments against the psychological approach. The aim of this chapter is to show that the biological theorist’s challenge to the transplant intuition can be met and that his additional arguments against the psychological approach are answerable. First, however, we need a more precise statement of the biological approach. What the biological approach claims is that we—you and I and any other readers of this essay—are animals of a certain kind, that is, human beings, members of the species Homo sapiens. Since we are persons it follows that some persons are human beings. The biological approach does not exclude the possibility of persons that are not human beings, or even animals, but it does insist that we are human animals, and as such have the persistence conditions of human animals. The second claim made by the biological theorist is that such persistence conditions involve no form 9 Persons, Animals, and Human Beings Harold Noonan 186 H. Noonan of psychological continuity whatsoever; they are entirely biological. For psychological continuity is never either a necessary or a sufficient condition of the identity over time of an animal. According to the biological theorist, then, things of very different kinds can be persons, and the persistence conditions of an entity that is a person of a particular kind will depend on the kind of thing it is. We are persons for whom the persistence conditions are entirely biological, but this will not be so for divine persons, or inorganic robotic persons. Thus there are no necessary and sufficient conditions for personal identity as such, of the type the psychological approach suggests, but for each kind of person there are necessary and sufficient conditions for the identity of persons of that kind. Olson develops this point by appeal to the familiar distinction between substance sortals, which tell us what a thing is, and phase sortals, which merely tell us, as it were, how it is during a certain period of its existence. Locke’s definition of a person as a “thinking, intelligent being . . . ,” he suggests, is not a definition of a substance sortal at all, but merely a phase sortal. To be a person, on this account, is merely to be an entity with certain capacities, and an entity that has such capacities may have existed before it gained them and may survive their loss; ‘person’ is merely a functional term, like ‘genius’ or ‘prophet’. Olson consequently proposes that for each of us there was a time, when he was a fetus, when he existed but was not a person, and for some of us there will be times in the future, after brain damage, when we are still in existence, but merely as human vegetables, not persons. It is an important point for Olson that we accept that in such a “vegetable case” the human animal that was once a person in the Lockean sense continues to exist, though not to be a person, and that each mature human animal was once a fetus. For if we accept these things we must accept that psychological continuity is not necessary for the persistence of the human animal. Nor, Olson insists, is it sufficient. In the familiar transplant case there may be dispute about whether the brain recipient is the same person as the brain donor (as the psychological approach dictates), but there is no denying that he is not the same human animal as the brain donor. Or rather, on Olson’s view, it is correct to say in this case that the brain recipient is the...