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Mark Young's avatar

I like Mike. But if you're going to talk about what's conceivable, then his rules for personal identity fail for identities in conceivable universes.

Consider Riker from ST:TNG. A transporter accident (pre-series) creates two copies of him: one on the Potemkin and one on Nervala IV. These copies are both William T. Riker (or as much so as any transporter-copy is). The version on the Potemkin goes on to become the Riker we meet in season 1, while the other version doesn't appear until series 6.

The two copies of Riker are both continuations of the Riker who was sent down to Nervala IV. They both have the same personal identity as the pre-away-team Riker. Nevertheless they have distinct personal identities afterwards. We have three identifiers:

(R1) Riker before the mission to Nervala IV.

(R2p) Riker on the Potemkin post mission to Nervala IV.

(R2n) Riker on Nervala IV after the Potemkin left.

R2p has the same personal identity as R1; R2n has the same personal identity as R1; but R2p and R2n have distinct personal identities. Personal identity is (conceivably!) not transitive. (Also not 1-to-1, since R1 is identical to both R2p and R2n, who are two beings.)

Time travel into your own lifetime shows this as well -- the present-me and the future-me have the same personal identity but also different personal identities.

Also cloning, as typically presented in science fiction. (Tho' at least here there's usually an original and a copy, and the original is typically taken to embody the "real" identity.)

Of course there are no Star Trek transporters or time travel or SF-style cloning in our universe, so Huemer's rules are actually fine for any real-life theory of personal identity.

Then again, Freaky-Friday type scenarios also don't happen in our universe, so the Ronnie Coleman story is just that -- something we can conceive of, but not evidence of the substance-hood of consciousness in reality.

One more thing. It would be possible to avoid the conceivability arguments above by holding that personal identies are not extended in time. You wouldn't have crapped your pants 21 years ago because that was an entirely different being. BONUS: no need to apologize for THEIR act of blaming Ellis. But then you'd be a completely different being now than the one that wrote the article I'm responding to. No chance of any two beings having anything like a conversation. Huemer should have noted that any reasonable theory of personal identities allows them to be extended in time.

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Talis Per Se's avatar

Better call soul

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