Presentation on theme: "Personal identity Michael Lacewing"— Presentation transcript:
Personal identity Michael Lacewing
Two kinds of identity Qualitative identity: two things are identical in their properties Numerical identity: there is just one thing (a=a) If one thing changes its qualities, does it remain the same thing? –He was a different person after the cancer scare –Who was? Change presupposes numerical identity Personal identity: what are the criteria for being the same (numerically identical) person over time?
One mind? Dualism: I am a mental substance; as long as the substance persists, I do Materialism: there is only matter - does this mean that I persist as long as my body does? Psychological theory: personal identity is continuity in psychological properties - even if these are transferred to another body
Lockes theory I am united by memory: I am the same person as I was at times I remember –But I cant remember every moment from the past –Overlapping chains of memory What of sleep? Shoemaker: causal dependence not just on memory but persistence through sleep Extend from memory to many psychological states
An objection The teletransporter malfunctions! –Both Kirks have overlapping chains of psychological states; are both Kirk or neither? We have qualitative identity, but not numerical –Not both: One person cannot be or become two people –Not neither: the same causal relation holds as in normal cases; whether Kirk is Kirk cant depend on whether another Kirk exist…? Something other than psychological continuity is needed for personal identity
Bodily theory Psychological continuity isnt enough, there must be continuity in matter Williams: more than 50% of my brain Animalism: we are animals, not simply embodied minds; personal identity means continuing as the same organism Teletransportation doesnt keep identity - it produces a replica
Brain transplants Is animalism or Williams right? If your brain is switched with another brain, which body are you in? Your original one or the one with your brain in? Your brain and mine are both erased and then reprogrammed with each others psychological states; now which body are you in?
Was I that baby? I have almost no psychological continuity with the baby whose body became mine So was I ever a baby? Option 1: we are essentially animals, and only persons for some time Option 2: we are essentially persons, and start to exist after the animals whose bodies we are in