There Is No Single Problem of Personal Identity, but Rather a Wide Range of Loosely Connected Questions

There is no single problem of personal identity, but rather a wide range of loosely connected questions. Here are the main ones:

Who am I? We often speak of one's "personal identity" as what makes one the person one is. Your identity in this sense consists roughly of those properties that make you unique as an individual and different from others. Or it is the way you see or define yourself. Or it may be the network of values and convictions that structure your life. We might call it your individual psychological identity. Your individual psychological identity is a property (or set of properties), and presumably one that you have only contingently: you might have had a different identity from the one you in fact have. Likewise, it is a property that you might have for a while and then lose: you could acquire a new individual identity, or perhaps even carry on without one. (Ludwig 1997 is a typical discussion of the Who am I? question.)

Personhood. What is it to be a person? What is necessary, and what is sufficient, for something to count as a person, as opposed to a non-person? What have people got that non-people haven't got? This is more or less equivalent to asking for the definition of the word person. An answer would take the form "Necessarily, x is a person if and only if Ð'... x Ð'...", with the blanks appropriately filled in. More specifically, we can ask at what point in one's development from a fertilized egg there comes to be a person, and what it would take for a chimpanzee or a Martian or an electronic computer to be a person, if they could ever be. (See e.g. Chisholm 1976: 136f., Baker 2000: ch. 3.)

Persistence. What does it take for a person to persist from one time to another Ð'-- that is, for the same person to exist at different times? What sorts of adventures could you possibly survive, in the broadest sense of the word 'possible'? What sort of thing would necessarily bring your existence to an end? What determines which past or future being is you? Suppose you point to a little girl in an old class photograph and say, "That's me." What makes you that girl, rather than one of the others? What is it about the way she relates then to you as you are now that makes her you? For that matter, what makes it the case that you existed at all back then? This is the question of personal identity over time. An answer to it is an account of our persistence conditions, or a criterion of personal identity over time (a "constitutive" rather than an evidential criterion: see the Evidence Question below).

Historically this question often arises out of the hope (or fear) that we might continue to exist after we die. Whether this is in any sense possible depends on whether biological death is the sort of thing that one could survive. Imagine that after your death there really will be