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From: jqb@netcom.com (Jim Balter)
Subject: Re: Exact Duplicate?, also Dennet (was Re: Brain and Body aspects of same thing.
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Date: Thu, 25 Jan 1996 21:12:48 GMT
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In article <4diqul$20o@pheidippides.axion.bt.co.uk>,
Donald Fisk <donald@srd.bt.co.uk> wrote:
>Bruce McAdam (bjm@dcs.ed.ac.uk) wrote:
>: In article <4d76oi$54j@copland.udel.edu>, greggt@copland.udel.edu (Thomas R. Gregg) writes:
>: [Article has been rearranged a bit]
>: > I would argue that the mind is somehow inextricably connected with the
>: > brain, so that if you removed someone's brain, you would also remove that
>: > person's identity, leaving their body a shell.  The new brain would come
>: > with a different consciousness and the new brain-body combination would be
>: > a different "person."  Further, I think that consciousness is not 
>: > distributed over the whole brain, but is a property of some brain area, 
>: > just as hearing and sight are properties of particular brain areas.  So 
>: > there is some brain area that you could transplant between people to make 
>: > them change identities, much as people change identities in fairy tales.
>
>: See Daniel Dennet's "Conciousness Explained" for an extremely good argument
>: against this view.  It also has arguments against the view that "hearing and sight
>: are properties of particular brain areas".
>:  
>: > If doctors were to replace a person's brain with an exact duplicate, would
>: > the person notice any difference?  This is quite a poser. 
>
>: How can it be an "exact duplicate" if someone can notice a difference?
>
>Consider two separate cases.
>
>(1) A person's brain is replaced, neuron by neuron, with electronic devices
>(with suitable electrochemical I/O), one for each neuron.   Would the
>resulting person possess the same identity?
>
>(2) A person's brain is copied, atom by atom.   His brain is then cut off
>where the brain stem is joined to the spinal column and replaced, by
>suitable microsurgery, with the exact replica.   Would the resulting person
>possess the same identity, or would the original (now disconnected, and
>probably dead) brain?
>
>Intuition suggests that identity would be preserved in case (1) but not
>case (2).   However, an external observer might not notice the difference
>in case (2), but would in case (1).   In both cases, the person would
>*think* their identity had survived, so asking them would be pointless.

*My* intuition suggests that your notion of identity is incoherent.
There is so such thing as an identity, which is possessed.  The laws of
conservation of matter and energy do not apply to identities.
"Identity" is a human concept involving the notion of continuity.

The Greeks played these games long ago.  If each plank of Theseus's ship is
replaced, one by one, is it still the same ship?  After you've thought about
it and debated it and come up with your answer, consider that the removed
planks have been reassembled as a separate ship.  Which is *really* Theseus's
ship?  Even trying to give an answer to this is a result of an improper
reification of identity.
-- 
<J Q B>

