Reply: OK, so just build into the criterion that duplication doesn't occur. This still gets what we were looking for: the possibility of immortality Memory Criterion(no competitor version or"MCncy"): person-stage y is a successor of x iff y really remembers x,'s experiences(directly ) and no other stage does, x and y are stages of the same person iff they are linked by successor stages Intrinsicness problem: Should my continued existence depend on whether there is someone else who happens to have the same memories? Whether I continue to exist should depend only on facts about me and my candidate future self, not on facts about who else happens to existReply: OK, so just build into the criterion that duplication doesn't occur. This still gets what we were looking for: the possibility of immortality. Memory Criterion (no competitor version or "MCncv"): person-stage y is a successor of x iff y really remembers x's experiences (directly), and no other stage does; x and y are stages of the same person iff they are linked by successor stages. Intrinsicness problem: Should my continued existence depend on whether there is someone else who happens to have the same memories? Whether I continue to exist should depend only on facts about me and my candidate future self, not on facts about who else happens to exist