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Article 4626 of comp.ai.philosophy:
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>From: smoliar@jit.iss.nus.sg (stephen smoliar)
Newsgroups: comp.ai.philosophy,sci.philosophy.tech
Subject: Re: Infinite Minds?
Summary: Charity begins at home.
Message-ID: <1992Mar20.121238.859@nuscc.nus.sg>
Date: 20 Mar 92 12:12:38 GMT
References: <1992Mar17.181431.20297@gpu.utcs.utoronto.ca> <1992Mar18.183651.26822@cs.ucf.edu> <1992Mar19.100550.10019@husc3.harvard.edu>
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Reply-To: smoliar@iss.nus.sg (stephen smoliar)
Organization: Institute of Systems Science, NUS, Singapore
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In article <1992Mar19.100550.10019@husc3.harvard.edu>
zeleny@zariski.harvard.edu (Mikhail Zeleny) writes:
>
>Pardon my intrusion, but what the fuck does Church's thesis (Turing, a
>student of his, was rather a latecomer) have to do with the claim of
>digital brain functioning?  As a matter of fact, McCulloch and Pitts, with
>their semantical finiteness (<=> digital functioning) assumption already
>implicit in the quaint title of their original AI manifesto, ``A Logical
>Calculus of the Ideas Immanent in Nervous Activity'', made an explicit,
>specious, unjustified identification of ``computability by an organism''
>with Turing computability (of course, this didn't stop them from making
>counterfactual claims contradicting the preceding: ``every net, if
>furnished with a tape [...] can compute only such numbers as can a Turing
>machine, [...and] each of the latter numbers can be computed by such a
>net''; --- pray tell, where does the tape come from?), concluding with a
>monumental misreading of Church's Thesis by conflating computability and
>effective computability: ``This is of interest as affording a psychological
>justification of the Turing definition of computability and its
>equivalents, Church's $\lambda$-definability and Kleene's primitive
>recursiveness: if any number can be computed by an organism, it is
>computable by those definitions, and conversely.''

There you have it, folks, right from the (metaphorical) pen of the man who
urged charity for Hilary Putnam!  Didn't one of our readers comment that you
only feel charity is deserved by those who agree with you?  It looks like he
got your number, Mikhail!

Those of us who have cracked our skulls at one time or another over the
McCulloch-Pitts paper would hardly deny that it is a sloppy piece of writing
(or that the sloppy writing does much to obscure the message).  Nevertheless,
as one becomes more familiar with the general subject matter, one discovers
that debugging the paper is not that difficult, if a bit tiresome.  This is
not so much a question of charity as one of a little mental elbow grease.

The reference to the tape, on the other hand, is simply a speculative gesture.
I have never read it as anything more than an attempt to raise the question of
whether or not such a tape exists at the biological level.  Given the way
cognitive science has been going, I am not sure that speculation would carry
much weight any more.
-- 
Stephen W. Smoliar; Institute of Systems Science
National University of Singapore; Heng Mui Keng Terrace
Kent Ridge, SINGAPORE 0511
Internet:  smoliar@iss.nus.sg


