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From: torkel@sics.se (Torkel Franzen)
Newsgroups: comp.ai.philosophy
Subject: Re: Minds, machines, and Godel
Message-ID: <1991Jan19.193717.9378@sics.se>
Date: 19 Jan 91 19:37:17 GMT
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In-Reply-To: chalmers@bronze.ucs.indiana.edu's message of 19 Jan 91 18:53:03 GMT

In article <1991Jan19.185303.25410@bronze.ucs.indiana.edu> chalmers@bronze.
ucs.indiana.edu (David Chalmers) writes:

  >The trouble with this refutation through inconclusiveness is that if it does
  >in fact turn out that we are able to discover enough about the human mind
  >(an empirical matter), then the Lucas argument applies as strongly as ever.

  Come now. If the Lucas argument is strengthened by (as yet purely
hypothetical) observations concerning the human mind, it is another
argument. In rejecting the Lucas argument I'm rejecting what is now
presented as a piece of reasoning from Godel's theorem. To take an
analogy: if somebody argues that there is life on Mars on the basis
of a vision, I reject his argument. If he argues that there is life on
Mars on the basis of a vision in combination with the findings of
an expedition to Mars, we are dealing with a new argument.

  >As for simulating the mind by a TM not being an empirical question; I don't
  >see why.  I'm talking about a complete simulation of human action, not just
  >some ill-specified notion of "mathematical judgment".  Then *given* such
  >a simulation ability, we can produce simulation of some stipulated aspect of
  >mathematical judgment without difficulty, as outlined in the previous
  >paragraph.

  The notion of 'simulation' at issue here is that of a Turing machine
generating (or accepting) those and only those arithmetical statements
provable by human beings. Your remarks about a 'complete simulation of
human action' don't at all touch on the questions involved. For
example, in the case of the consistency of ZFC, which 'human action'
do you want to simulate: the assertion that ZFC is evidently
consistent, or the assertion that there are no grounds for claiming
that ZFC is consistent? Both of these 'actions', and others as well,
are found among mathematicians.