I. Introduction

As many have noted, what is often called the “problem” of personal identity can be understood either as a metaphysical issue or as an epistemological (and somewhat more practical) issue. Metaphysicians typically want to know what it is for one individual to be the same person as another. People undergo many changes over time, and some people resemble others quite closely The metaphysician wants to know, for example, what makes me—the chronologically challenged, mostly bald philosopher Stephen Braude—the same unique individual as the infant who appeared on the scene many years earlier, despite the considerable evolution in my appearance and in my psychology during the interim. However, epistemologists are concerned (at least sometimes) with a different problem: how to decide if an individual is the same person as someone else. For example, are these decisions rooted in judgments about physical continuity, psychological continuity, or both? In virtue of what, for example, do we identify a person as me, despite (so I'm told) my remarkable resemblance to other chronologically and follically challenged individuals? Granted, in real life this potential problem seldom stops us in our tracks. Although some have trouble distinguishing identical twins, and although we sometimes mistake a person for someone else, those problems are uncommon, and usually they are quickly resolved. In fact, that is about as difficult as it gets for everyday identifications.