X-Message-Number: 3779
Date: Thu, 2 Feb 1995 01:26:19 -0500 (EST)
From: Charles Platt <>
Subject: Convergent/Divergent identity

Steve Harris (whom I basically agree with) writes:

> Now, two brains [ . . . ] may be quantum
> identical for an instant-- sort of like the carbon-14 atoms. 
> After that, however, they will evolve to different quantum
> states

Yes, but this does not guarantee that they will behave differently on the
macro scale. The electrons in my computer are dancing very differently
from one day to the next, but the aggregate behavior is the same, because
the architecture imposes a defined structure, and the system has some
error-correction built in. 

Steve recognizes this possibility in human beings when he says:

> If personality is the product of a much more grainy
> brain neural states which are more resistant to quantum 
> differences, then such states will not diverge until quantum
> differences get large enough.  

But how large is "large enough"? I see no evidence that any divergence in
quantum states will be big enough to make a *noticeable* difference on the
macro scale if the brain is self-stabilizing. Even individual neurons or
groups of neurons may not make noticeable changes in aggregate behavior. 
Bear in mind cases where whole chunks of brain are lost in accidents,
without necessarily causing personality changes. 

> At some further point in
> the future, mental state will have diverged enough to change
> behavior.

I don't see that you have proved this, Steve. We basically do not know if
behavior of the brain is convergent or chaotic. If it's convergent, you
can give it a nudge and it will self-correct over time. If it's chaotic, a
very small nudge can create big behavior changes. But any therapist will
tell you that behavior is very DIFFICULT to change--after a certain age.
Moreover, everyday experience tells us that we "bounce back" and "recover
ourselves" after mood-altering events. This all suggests to me that the
brain has built-in error correction and is basically stable, as I think it
would have to be for us to have evolved successfully. A chaotic-type
system would be far too reactive; it would go running off in all
directions, and people would be incapable of forming stable communities. 
(Like cryonicists.)

> brains, being analog devices, are NOT like computers

Well, brains might be like *analog* computers! In any case, any analog
process can be simulated digitally (as happens on a routine basis inside
my CD player). On a quantum level, matter behaves digitally anyway, in 
the sense that there are no fractional quantum states. This "digital 
distinction" is a red herring I think.

You point out that "me" today may not be the same as "me" yesterday. 
True. But I can just as well point out that "me" yesterday made exactly
the same kind of silly mistakes as "me" today, despite many years in which
I have attempted to correct my behavior. In fact, for all I know, as a
result of a memory lapse I may have already had a very similar discussion
with you on this point, and I think it is likely that an uploaded version
of me, or an atom-for-atom copy of me, would use exactly the same words to
say exactly the same thing 100 years from now. 

Whether one finds this depressing or reassuring is a matter of 
perspective, I guess.

PS. If I encountered an exact copy of myself, I imagine a scenario like 
the one in the Chuck Jones cartoon, DUCK AMUCK, where Daffy Duck climbs 
out of his movie frame to confront himself in the next frame along. 

Charles Platt, 1133 Broadway (room 1214), New York, NY 10010
      Voice: 212 929 3983      Fax: 212 929 4467

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