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From: mangoe@umcp-cs.UUCP (Charley Wingate)
Newsgroups: net.philosophy,net.math
Subject: Mind as Turing Machine
Message-ID: <1996@umcp-cs.UUCP>
Date: Sun, 27-Oct-85 01:08:05 EST
Article-I.D.: umcp-cs.1996
Posted: Sun Oct 27 01:08:05 1985
Date-Received: Thu, 31-Oct-85 21:12:55 EST
References: <859@whuxlm.UUCP> <10810@ucbvax.BERKELEY.EDU>
Organization: U of Maryland, Computer Science Dept., College Park, MD
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Xref: linus net.philosophy:2670 net.math:2070

There are a number of reasons why I doubt that the mind is in fact like a
turing machine.

As James Lewis pointed out, neurons are essentially analog devices; they
typically respond to input *levels* rather than to descrete stimulae.  If
this holds up in general, it means that the state space of the mind is
essentially continuous.  THe brain also has a lot of analog inputs, posing
similar problems with respect to the "tape".

At the neural level, one typically sees random behavior.  Increasing
stimulae tend to increase or decrease the rate or probability of firing, but
the action is distinctly unlike the firing structure of a computer.  State
transitions would seem therefore to be probabilistic.

Lastly, it's certainly clear that we cannot now model even moderately small
portions of the mind through computers.  I think it is reasonable to ask
those who wish to assert the turing machine-ness of the mind need to show
some method by which the mind can be translated into an equivalent turing
machine, even if this translation is computationally infeasible  (which is
indeed likely).  Without such an algorithm, I think there is reasonable
cause not to accept the hypothesis.

Charley Wingate