24.00: Problems of Philosophy Prof. Sally Haslanger October 17, 2001 Personal Identity II Problem of synchronic identity for persons: under what conditions are two simultaneous person-events events in the life of the same person? Problem of diachronic identity for persons: under what conditions are two person-stages stages in the life of a single person. In particular, what makes a particular person-stage a continuation of me as I am right now? Background desiderata: an account of personal identity should allow for the possibility of anticipation and memory, i.e., of individual psychological connections between different person stages. It should also allow us to justify our practices of recognizing and identifying persons. Soul criterion: x is the same person as y iff x and y have the same soul. Or, in the terminology of stages: Person-stage x is part of the same person as person-stage y iff there is a (single) soul S that is present in both x and y. Body criterion: x is the same person as y iff x and y have the same living human body. Or, in the terminology of stages: Person-stage x is part of the same person as person-stage y iff x and y are person-stages linked by bodily continuity (where bodily continuity is understood in terms of the continuity of a living human body). Sam's criticisms of the body criterion: i) If I were my body, then I would have no special access to myself, e.g., in order to know I am present in a situation, like everyone else, I would have to determine whether my body is present. But it seems that we do have special access to ourselves: when I wake up in the morning I can tell that I exist and am the same person who went to sleep before I have any information about the existence or condition of my body. So the body criterion does not do justice to our practices of self-recognition and self-identification. ii) It is possible to be the same person without the same body. Although it may not be physically possible for persons to switch bodies, it is certainly conceivable that you could wake up in the morning in your roommate's body (and vice versa), or in a non-human body. But if this is conceivable, then the body criterion doesn't capture what it is to be the same person over time, i.e., our concept of person. Locke's idea: continuity of consciousness Synchronic unity: Person-events e and e' occurring simultaneously are parts of the same person-stage iff e and e' are together part of a unified consciousness at that time. Diachronic unity: Person-stages x and y are parts of the same person iff x and y are together part of an extended consciousness; we might think of this as a kind of extended psychological continuity. Aiming for an account of diachronic (personal) identity using Locke's insight, consider: Memory Criterion (basic form): x and y are stages of the same person iff y remembers x's experiences, thoughts, feelings, etc. (either directly or indirectly), or vv. (Call this "memory linked".) Circularity Problem: this criterion will work only if we insist that the memories be "genuine", not just "seeming memories". But the best account of genuine memories seems to rely on the very notion we're trying to define. Roughly: x and y are stages of the same person iff y really remembers x's experiences, etc. But to cash out "really remembering" we need: y really remembers x's experiences, etc., iff y seems to remember them, and x and y are stages of the same person. This is circular. Reply: There is a better account of "really remembering" that avoids this: y really remembers x's experiences, etc., iff y seems to remember them, and y's memories of x's experiences are caused "in the right way". What is "the right way"? Perhaps, "some especially reliable way"? This suggests a new version of the memory criterion that avoids the circularity problem: Memory Criterion (causal continuity version or "MC ccv "): x and y are stages of the same person iff y really remembers x's experiences, etc. (the memories are caused "in the right way") either directly or indirectly. (Call this "real-memory linked".) The MC ccv appears to allow for immortality because it is possible for God (or some other mechanism) to take all your memories on your deathbed and imprint them in another body in the afterlife. The "consciousness" in this other body seems to have all of your memories; if the mechanism (be it God or some other) is sufficiently reliable, then by MC ccv you exist in the afterlife. HOWEVER, why can't such a mechanism imprint the memories in more than one body? Would there then be two of you in the afterlife? Duplication Problem: on the causal continuity version of MC it is possible that person stage x is memory linked with two different stages y and z (e.g., in different bodies) that are not memory linked, so that one person-stage would have two different futures. This is impossible. If G is the same person as A, and G is the same person as B, then A must be the same person as B. 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 "MC ncv "): 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.