1. What is the Problem of Personal Identity?
Locke posed the problem of personal identity in one brief question, “What makes the same person?” This formulation is deceptively simple. My aim is to offer a new interpretation of the problem and to suggest a method for finding a solution.
Investigations of personal identity are usually cast in terms of finding the criterion for personal identity. Yet talk of criteria is ambiguous. In one sense of the term, the criterion of personal identity would be special evidence for personal identity. According to the second usage, the criterion of personal identity would be that state of affairs for which evidence for personal identity is evidence. We will not be concerned with the first construal. On that reading, the problem of personal identity would be an epistemological issue. But the basic question concerning personal identity, “What is one person?” does not appear to be an epistemological question.