John Clark (
Sat, 21 Nov 1998 14:08:20 -0500

Hash: SHA1

      >>It two things can be exchanged and no change can be detected by the
      >>outside world then the two things are identical.

    >christophe delriviere <
>Ah, but we are not in quantum mecanics here, brains are macroscopic >objects, so we can track their positions in space-time.

How can you track them? If your brain and mine are identical then there is no way to determine if they've switched positions or not, and it wouldn't matter if they did.

>A brain is also strongly defined by his position.

How? The input position of the sense organs is the only thing that's important, the only restriction is that the sense organs are not so far away that time delays caused by the speed of light start to become important. A brain by itself has no way to determine it's position in space, or the passage of time for that matter. I could stop your brain for a thousand years, speed it up by a factor of a billion, or even make it run backward and you'd never notice a thing. In the future "people" might not know or care where their brain was, or if they were operating on their primary or backup brain.

>even if everything you know I know, and everything I see
>feel and hear you see and feel and hear, even if we are for a moment
>complete identical copies, we can't be exchanged.

Why? Exactly what would be different?

John K Clark

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