X-Message-Number: 15300
Date: Tue, 9 Jan 2001 07:35:04 -0500
From: Thomas Donaldson <>
Subject: once more on computers and people

Hi everyone!

Someone other than Mike Perry also seems hypnotized by Turing machines.
He claims that a human brain could be imitated (if I read him right)
by a single fast processor. While a very small brain could probably
be imitated, it doesn't follow from that that much larger brains 
could be so imitated. The problem becomes exponentially harder the
more neurons used. I would like to see his explicit calculations on
this issue.

He also disliked what I said about another issue which may affect
whether or not a Turing machine could imitate a human brain: he claimed
that imitations showing growth and loss of neurons and changes in their
connections had already been implemented. Again, I'd like to see his
references. The work on computer models of brains is one which I
try to follow myself, not because I believe that computers (as we
know them now) could imitate complete brains but because it does
produce one way to test our ideas about how brains do various 
operations. 

I will finally point out that in my discussions I have quite deliberately
NOT claimed that we could not produce a device which imitated the
workings of a human brain. That's not what I'm talking about at all.
I have suggested problems with producing COMPUTERS which imitate
human brains COMPLETELY ... at least any computers as we now know
them. The question I am raising is that of whether or not Turing
machines provide an adequate model for ALL thinking/feeling machines.
Of which human beings provide one case (and note that I did not 
say "thinking" or "feeling" alone). 

And no, our present machines fail utterly to match living things
on some characters essential to living in the real world: self-repair
one of the most outstanding ones. Without self repair an independent
creature isn't going to survive very long at all.

		Best and long long life for all,

			Thomas Donaldson

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