Parfit on Personal Identity

1. Parfit on Personal Identity Fission, Fusion, and Survival

2. Fission, Fading, and Grounding Problems for Neo-Lockeanism

3. Fission, Grounding, and Fading • We saw on Tuesday that one worry about Neo-Lockean (psychological) criteria for personal persistence was that didn’t seem to be one-one. • And, intuitively, survival is intrinsically grounded. • Another problem: persistence seems to admit of degree. Parfit will defend a Neo-Lockean account of survival arguing that what matters for personal persistence is not identity. Because identity is tough…

4. Identity Problems for S-T Objects • Identity is transitive: if a = b and b = c then a = c • But there are cases in which identity seems to be one-many rather than one-to-one, so that a = b and b = c but a ≠ c • Identity does not admit of degree • But spatio-temporal objects can undergo gradual change and “become” other things • Intuitively identity is intrinsically grounded: nothing other than the intrinsic properties of a and b should make any difference to whether a = b is true • But there are cases where we can avoid violations of transitivity of identity by denying intrinsic grounding.

5. Personal Identity • All these problems arise in a particularly virulent form when we consider the identities of persons. • Parfit will consider • “fission” and “fusion” cases in which transitivity is violated • cases in which personal survival seems to me a matter of degree • We’ll consider the general problem posed by the identities of spatio-temporal objects generally and then the way in which these problems arise in the special case of personal identity. And the question of intrinsic grounding.

6. Personal Identity and Survival • What matters for survival? • “Surviving” in the memory of others? Having your good deeds live after you? • I don’t think so! • The continued existence of your mummified corpse? • The continued existence of a spiritual substance? • Is the existence of anything identical to me in the future a necessary condition on “what matters” for survival?

7. Is identity what matters for personal persistence and survival? What matters

8. Does identity matter? Derek Parfit, in a series of articles in the 1970s and his1984 Reasons and Persons argues that identity is not “what matters” for personal persistence/survival.

9. Personal Identity & What Matters • Parfit says that his revisionary account of personal identity has implications for the way we live our lives • Moral issue: self-interest and impartiality • Contemplating old age, death, and other future bads • Does the identity question always have an answer with regard to persons? • Is what matters for personal survival (recognizing person as a ‘forensic term’) identity? E.g. • Anticipating future events • Being held responsible for past actions

10. Problem: Survival Not One-to-One • ‘Fission cases’, e.g. amoebic division, brain hemisphere transplant, etc. suggest that I can survive as two different people. • I don’t regard it as death, I anticipate future events that occur to them, and they remember (or ‘remember’) events that occurred to me. • Fantasy case of the math test similarly suggests I survive, if temporarily, in 2 streams of consciousness.

11. Identity is not ‘What Matters’ • Argument: what matters for survival not one-to-one • Identity is one-to-one • What matters for survival is not one-to-one • Therefore, what matters for survival is not identity • Argument: what matters for survival admits of degree • Identity is does not admit of degree • What matters for survival does admit of degree • Therefore, what matters for survival is not identity

12. Psychological Continuity Matters Williams • What matters for survival is identity • Identity is one-to-one • What matters for survival is one-to-one • So, cannot be psychological continuity Parfit • What matters for survival is psychological continuity. • Psychological continuity is not one to one. • What matters for survival not one-to-one • So, what matters for survival is not identity

13. Parfit: Survival isn’t identity • What matters for survival isn’t a one-to-one relation • What matters in survival admits of degree • What matters for doesn’t presupposes identity • Against circularity objection to the memory criterion • Butler: ‘Memory presupposes personal identity and therefore cannot constitute it’

14. The Circularity Objection • Objection: x remembers doing and action or experiencing an event only if x is (identical to) the person who did the action or experienced the event. • Response: I q-remember an experience if • I have a belief about a past experience which seems in itself like a memory belief • Somebody did have such an experience, and • My belief is dependent upon this experience in the same way in which a memory of an experience is dependent upon it.

15. What matters admits of degree • Fusion and q-intending • We have to compromise vacation plans (in fusion cases) • Psychological continuity and connectedness • Continuity is, but connectedness isn’t, transitive • Compare actual practices • Time Preference: discounting the future • Culpability for past actions

16. Who am ‘I’? • Being a ‘past self’ or ‘future self’ a matter of degree • Connectedness matters and it’s not transitive • Puzzle cases • The fission-fusion beings • How would they think of themselves? • Longevity • Is it I? An earlier or later self? Or what?

17. Parfit: Real Life Consequences • The Principle of Self-Interest has no force • The principle of self-interest is normally supported by the principle of biased rationality--biased to persons identical to us. But identity is not what matters. • Egoism undermined • Concern for our own remote future undermined • Parfit’s Conclusion: if we’re better off without self-bias and ego concern, if we should be more impartial, then the revised understanding of personal survival is the beginning of all (or at least some) wisdom.

18. Branching cases and identity Fission

19. A Person Undergoes Fission We split Jones brain and transplant the two hemispheres (which duplicate information) into the otherwise brainless bodies of Smith and Brown. After the operation, both Smith-Jones and Brown-Jones sincerely claim to be Jones. They can’s both be identical to Jones! Smith-Jones Brown-Jones Jones

20. Simple Fission and Fusion Fusiontwo things become one Fissionone thing becomes two time

21. ’Becoming’ Can’t Be Identity! = = = = = = Fusiontwo things become one Fissionone thing becomes two time

22. Another Transitivity of Identity Problem The doctrine of the Trinity!

23. Why can’t Jones be both after fission? ≠ Smith-Jones Brown-Jones We can’t say that both Smith-Jones and Brown-Jones are Jones because Smith-Jones Brown-Jones. Transitivity of Identity violation! time = = Jones

24. Extrinsic grounding and best candidate accounts Grounding

25. The Best Candidate Option Suppose only this had happened When an amoeba divides symmetrically we say the mother amoeba ceases to exist. If however the amoeba just ‘lost’half of its stuff and then regenerated so that only one amoeba remained at the end of the process we might want to say that the mother amoeba survived

26. Best Candidate Theory Actual World Another Possible World New Amoeba Same Old Amoeba New Amoeba Old Amoeba Old Amoeba At the Actual World, Amoeba survives the loss of half its body; at Another Possible World the ‘lost’half becomes a new amoeba. Since there are two equally good candidates, and both can’t be Old Amoeba, neither is: Old Amoeba ceases to exist.

27. Asymmetrical Fission The ship wherein Theseus and the youth of Athens returned [from Crete] had thirty oars, and was preserved by the Athenians …for they took away the old planks as they decayed, putting in new and stronger timber in their place, insomuch that this ship became a standing example among the philosophers for the logical question of things that grow; one side holding that the ship remained the same, and the other contending that it was not the same.

28. The Continuously Repaired Ship • Things can survive the gradual replacement of parts • Suppose the planks that composed the Ship of Theseus were gradually replaced until none of the original planks is part of the Continuously Repaired Ship at the end of the process • If you claim that it wouldn’t be the Ship of Theseus then you have to say at what point the Ship ceases to exist.

29. The Continuously Repaired Ship Survives • We can’t say that with the replacement of each plank the resulting ship becomes ‘less identical’to the original Ship of Theseus until it ceases to be identical altogether since identity doesn’t admit of degree • It would be deeply counterintuitive to say that there is a crucial plank (first, last or something in between) • Things can survive the gradual replacement of all their original parts so… • The Continuously Repaired Ship = The Ship of Theseus

30. The Plank Hoarder’s Ship • Things can survive disassembly and reassembly • Suppose the Ship of Theseus had been disassembled and cast off planks reassembled by a Plank Hoarder. • We want to hold that artifacts like ships, bicycles, (mechanical) watches, etc. can be taken to bits and reassembled—it happens all the time! • Some things in fact are made to be disassembled and reassembled for storage or for shipping so… • The Plank Hoarder’s Ship = The Ship of Theseus

31. The Ship Repaired AND Reassembled ≠ The Continuously Repaired Ship The Plank-Hoarder’s Ship We can’t say that both the Continuously Repaired ship and the Plank-Hoarder’s Ship are the Ship of Theseus because The Continuously Repaired Ship ≠ The Plank-Hoarder’s Ship Transitivity of Identity violation! time = = The Ship of Theseus

32. The Ship Repaired AND Reassembled ≠ The Continuously Repaired Ship The Plank-Hoarder’s Ship The Ship of Theseus (we agreed) could survive either the gradual replacement of all its parts or (we agreed also), it could survive disassembly and reassembly. So why can’t it survive as either--depending? time = ≠ The Ship of Theseus

33. The Ship Repaired AND Reassembled The Plank-Hoarder’s Ship The Ship of Theseus (we agreed) could survive either the gradual replacement of all its parts or (we agreed also), it could survive disassembly and reassembly. PHS is the Theseus if CRP doesn’t exist? time = The Ship of Theseus

34. The Ship Repaired AND Reassembled ≠ The Continuously Repaired Ship The Plank-Hoarder’s Ship The Plank-Hoarder’s Ship would have been the Ship of Theseus if it weren’t for the Continuously Repaired Ship, which is the ‘best candidate for being the Ship of Theseus. Intrinsic Grounding violation! time = ≠ The Ship of Theseus

35. Best Candidate Theory Actual World Another Possible World Plank-Hoarder’s Ship Plank-Hoarder’s Ship Continuously Repaired Ship Ship of Theseus Ship of Theseus On this account identity is extrinsicly grounded—the Continuously Repaired Ship fails to be identical to the Ship of Theseus because of an extrinsic property, viz.its coexisting with the Continuously Repaired Ship. But maybe this is OK…

37. Best Candidate Theory Actual World Another Possible World Modern Italian Modern Italian Dead, written Latin Roman Latin Roman Latin It seems plausible to adopt a best candidate theory when it comes to the identities of languages through time: Italian is no further from Latin then English is from Anglo-Saxon but in the absence of any better candidate we think English is the same language as Anglo-Saxon, a.k.a. “Old English.”

38. Best Candidate Theory Actual World Another Possible World Other Germanic Languages English English Western Germanic Western Germanic But suppose Western Germanic hadn’tsplit into different modern languages but just changed in one direction. Then we might want to say that Western Germanic survived as English—though radically changed.

39. Best Candidate Theory Western Germanic morphed into modern Flemish, Dutch, German, Frisian and English But, unlike Latin, it didn’t survive unchanged alongside modern Germanic languages. Arguably, all these languages are equally good candidates for identity with Western Germanic, so this is a case of symmetrical fission To identify all these distinct languages with Western Germanic would violate Transitivity of Identity so We say that Western Germanic has ceased to exist and has been replaced by English and other modern Germanic languages

40. Best Candidate Theory: The Dividing Self Actual World Another Possible World Brown-Jones Brown-Jones Smith-Jones Jones Jones Smith-Jones and Brown-Jones can’t both be Jones since that would violate Transitivity of Identity! So according to Best Candidate Theory we get this implausible result.

41. Counterintuitive Results • The Best Candidate solution is implausible • At the Actual World, Jones hopes that one and only one of his brain hemispheres will survive because if both do he’s as dead. • At Another Possible World, Brown-Jones is grateful to Smith-Jones for existing because if Smith-Jones hadn’t existed he wouldn’t. • Even if a best candidate theory is ok for languages it is very implausible as an account of personal identity in the fission case because it makes our existence and survival depend on external factors that seem entirely irrelevant.

42. Identity is all or nothing but personal persistence admits of degree Fading

43. Complex fission-fusion is even worse! • Parfit imagines a species of individuals who undergo fission every spring and fusion every fall. • Who am I? Which future(s) should I care about? Fall Spring

44. Is continuity a matter of degree? • The complex fission-fusion case suggests that psychological continuity may be a matter of degree. • Lewis suggests that in the Methusalah case psychological continuity may be a matter of degree also. { { { {

45. Methusalah(not to scale) Consider Methuselah. At the age of 100 he still remembers his childhood. But new memories crowed out the old. At the age of 150 he has hardly any memories that go back before his twentieth year. At the age of 200 he has hardly any memories that go back before his seventieth year…When he dies at the age of 969 he has hardly any memories that go beyond his 839th year. { { { { time

46. Personal Survival and Identity • Does identity matter for survival? • Problems • Identity is one-to-one • Intuitively, survival is intrinsically grounded • Identity does not admit of degree • So, Parfit argues, identity is not what matters for survival. • But Lewis argues to the contrary that it does.

47. Lewis: Identity Matters! To be continued