Even philosophers who believe there is a single “problem of personal identity” conceive of that problem in different ways. They differ not only in their ways of stating the problem, but in the parts of philosophy to which they assign it, and in the resources they feel entitled to call upon in their attempts to deal with it. My topic in this paper is an eighteenth-century uncertainty about the place within philosophy of the problem of personal identity. Is it a (...) problem in metaphysics, or a problem in ethics? Here I try to show that the boundary between ethics and metaphysics was—for a line of philosophers beginning with Locke, continuing with Shaftesbury, and ending with Hume—a shifting and sometimes disputed one. I hope what I have to say will help to clarify a longstanding problem in the interpretation of Hume: his motive for repudiating, in the Appendix to the Treatise, the account of judgments of personal identity and simplicity he had provided in Book I. (shrink)