Abstract

This dissertation is on the topic of personal identity over time. Thus my concern is with problems having to do with the conditions under which a person who exists now may accurately be said to have existed years ago, or to exist years from now. ;Proponents of a psychological criterion of personal identity believe that one survives just in case one's psychological characteristics stay more or less constant, or develop in some orderly way. According to most proponents of a physical criterion, one survives just in case one continues to have the same brain, and that brain continuously realizes various psychological capacities. ;I discuss and criticize several approaches of both the psychological and the physical sorts, and the implications of various kinds of thought-experiments for their plausibility. I argue that none of these approaches ought to be accepted. In particular, I discuss the psychological criteria of H. P. Grice, John Perry, Sydney Shoemaker and Derek Parfit. I discuss the physical criteria of Peter Unger, Mark Johnston, and Peter van Inwagen. I defend a Lockean view of personal identity. ;Locke believed that a person is "a thinking intelligent being that has reason and reflection, and can consider itself as itself, the same thinking thing in different times and places." On Locke's view, a person is an object, distinct from but related in some way to a human being. Persons possess psychological properties essentially. The essential properties of humans are biological properties. ;I do not dispute Locke's definition of personhood. However, I disagree with Locke on the survival conditions for humans, and I reject his dualist conception of human persons. I deny that there exists any entity for which personhood is an essential property. Instead, being a person is a temporary and non-essential property of humans. I am essentially a human, and for most of my life I am also a person, by virtue of my possession of the requisite psychological properties. I remain the same person for as long as I remain the same human; and continue to have these psychological characteristics