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Article 1746 of comp.ai.philosophy:
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>From: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: comp.ai.philosophy
Subject: Physical limits when programming neurons and minds
Message-ID: <57751@netnews.upenn.edu>
Date: 29 Nov 91 14:35:03 GMT
References: <43772@mimsy.umd.edu> <288@tdatirv.UUCP>
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Reply-To: weemba@libra.wistar.upenn.edu (Matthew P Wiener)
Organization: The Wistar Institute of Anatomy and Biology
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In-reply-to: sarima@tdatirv.UUCP (Stanley Friesen)

In article <288@tdatirv.UUCP>, sarima@tdatirv (Stanley Friesen) writes:
>This also is my main problem with the 'anti-AI' crowd.  I have yet to see
>any properly defined, verifiable definitions of some property possessed by
>neurons that is not, or cannot, be programmed into a digital computer.

I have yet to see every physical property of a neuron programmed.  I
have yet to see any evidence that this is possible.  The work of Pour-El
and Richards has shown that certain physically plausible PDEs do not
have computable solutions, so until we have an incrediblely greater
amount of knowledge of the physics of neurons, the belief that every
property of neurons is programmable is at best tentative.

But for the sake of argument, let's assume that neurons can be digitally
simulated.  Even with that much conceded, you still have a leap of faith:

>If every property of a neuron is programmable, then so is intelligence.

This does not follow in the least.  If our brains exploit quantum
cryptography to get an internal sense of privacy, then short of a
revolution in physics, there is no way you can simulate our minds
on a digital computer.  There may indeed then be a different way
to get digital intelligence, but it will not be found via the above
implication.

This is not such a far out possibility.  Gell-Mann and Hartle have
a rather interesting paper in the Zurek Santa Fe anthology on the
physics of information and complexity theory.  They outline their
approach to solving the quantum measurement problem--that is, why
does the quantum world appear classical?  They claim that quantum
mechanical situations can, under the right circumstances, decohere,
meaning that wavefunction interference goes to zero.  And that for
macroscopic objects, the decoherence time is virtually instantaneous.
They end their paper with the speculation that "complex adaptive
systems" would evolve into those right circumstances that lead to
decoherence.  Why?  Because observing a classical world leads to
better predictability.

In other words, Gell-Mann and Hartle are suggesting that a particular
quantum mechanical configuration is an essential part of our minds.
And so Bell's inequality may prevent any digital computation from
ever being a simulation of our minds.
-- 
-Matthew P Wiener (weemba@libra.wistar.upenn.edu)


