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Descartes

Descartes. I am essentially rational, only accidentally an animal ‘essentially’ = logically necessarily Strictly speaking, I’m not even accidentally an animal, for I’m not an animal at all; I’m (contingently) embodied

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Descartes

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  1. Descartes I am essentially rational, only accidentally an animal • ‘essentially’ = logically necessarily • Strictly speaking, I’m not even accidentally an animal, for I’m not an animal at all; I’m (contingently) embodied The demon thought experiment shows that I could (logically possibly) exist without my body, so I am not identical with my body

  2. John Perry “A Dialogue on Personal Identity and Immortality” • Possibility of survival after death as entrée to thinking about identity of persons • Logical possibility, not probability

  3. Qualitative Identity: • Being exactly similar Numerical Identity: • Being one and the same “She’s not the same person since her religious conversion….”

  4. The Soul Theory: I am my soul x and y are the same person iff x has (is) the same soul as y Soul=mind?

  5. Problem with the soul theory • Souls are immaterial, so we have no evidence for reidentification of souls • But we do have evidence for reidentification of persons • Therefore, persons are not identical with souls

  6. Argument for premise 1: • Souls perceived only indirectly, by assumption of same-soul-same-body principle • This principle cannot be a priori, since it isn’t necessary • It cannot be a posteriori, since there’s no empirical evidence for it (and couldn’t be!) • Therefore, there’s no evidence for the principle

  7. The Body Theory: I am my body x and y are the same person iff x has (is) the same body as y Conditions for sameness of body? (Ship of Theseus)

  8. Arguments against the Body Theory: • You wake up and you know who you are, without having identified your body yet. • Mind transfers

  9. John Locke:(1632-1704) I am a sequence of causally connected experiences

  10. Psychological Continuity Theory x and y are the same person iff the psychological states of x are appropriately linked to the psychological states of y • ‘appropriately linked’? • Locke: memory: • x = y iff the later of the two can remember the experiences of the earlier

  11. Teletransportation Person is disassembled, reassembled elsewhere

  12. Teletransportation Person is disassembled, reassembled elsewhere

  13. Teletransportation Person is disassembled, reassembled elsewhere

  14. Possibilities: A. Matter is transferred

  15. Possibilities: A. Matter is transferred

  16. Possibilities: B. Only information is transferred

  17. Possibilities: B. Only information is transferred

  18. Argument against Psychological Continuity Theory: • If you can replicate one, you can replicate two. Since they aren’t both identical with me, it seems that neither is • So teletransportation is suicide

  19. Personal Identity redux Soul theory Body theory Psychological continuity theory Fictionalism: strictly speaking, persons don’t endure over time; we attribute a fictional identity

  20. Ego theory: underlying subject of experiences: a substance in the technical sense (usually immaterial substance)

  21. Bundle theory: collection of mental events: there is (in a sense) no self

  22. David Hume1711-1776

  23. No concept of enduring self • If you can’t experience something, you can’t conceive it • Introspection reveals only train of perceptions, no enduring subject of perceptions • Therefore, we don’t experience an enduring self • Therefore, an enduring self distinct from these perceptions is literally unintelligible.

  24. Why do we believe in enduring things? Observing a smooth succession is very similar to observing an enduring object, so we mistake the former for the latter. We ascribe identity when: • changes are proportionately small • changes are gradual • changes don’t alter purpose of the whole All this shows that identity is ascribed, rather than a real property of the objects

  25. Parfit: argument for bundle theory • If ego theory is true, there should be hard and fast facts about whether x and y are the same • But there very often aren’t such facts • Therefore, the ego theory is false • The only alternative is the bundle theory • Therefore, the bundle theory is true

  26. Parfit: argument for bundle theory • If ego theory is true, there should be hard and fast facts about whether x and y are the same • But there very often aren’t such facts • Therefore, the ego theory is false • The only alternative is the bundle theory • Therefore, the bundle theory is true

  27. Teletransportation with partial material preservation: • 2% new matter? • 50% new matter? • 98% new matter?

  28. Split brains

  29. Two streams of consciousness: one ego or two? • 1=1+1? • Suppose hemispheres placed in new bodies, live separate lives. Is one of them you? • Which one?

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