Abstract

I see someone who looks vaguely familiar. I wonder if he could be the same person I had a fight with on my birthday ten years ago. I hear that some scientist has received the Nobel prize in chemistry for some work very similar to that which interested the brightest boy in my chemistry class twenty years ago. I wonder if that scientist and the brightest boy might be the same person. What facts, if they could be discovered, would be decisive in answering these questions? Are there any facts that, if it turns out that they do not obtain, would show conclusively that the two people are not the same person? That is, are there any necessary conditions for personal identity? Are there any facts that, if it turns out that they do obtain, would show conclusively that the two people are the same person? That is, are there any sufficient conditions for personal identity?