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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: A rock implements every FSA
Message-ID: <1992Mar18.194252.7849@bronze.ucs.indiana.edu>
Organization: Indiana University
References: <45005@dime.cs.umass.edu> <1992Mar18.014416.9980@husc3.harvard.edu> <1992Mar18.102043.20148@csustan.csustan.edu>
Date: Wed, 18 Mar 92 19:42:52 GMT

In article <1992Mar18.102043.20148@csustan.csustan.edu> tom@csustan.csustan.edu (Tom Carter) writes:

>  1) My objections to Putnam's `theorem' don't have to do with
>      `counterfactuals' -- he simply got the definition of FSA wrong.  Now,
>      perhaps he actually thinks that his definition (which he essentially
>      leaves implicit) is equivalent to the standard definition, or perhaps
>      he doesn't understand the standard definition (in particular, the
>      critical role of the input); however, his "no hope" comment is
>      certainly suggestive that he knows he has left out something crucial.

Actually, your argument comes to much the same thing as mine.  Putnam
would say that his construction *can* handle FSA's with inputs,
straightforwardly.  That just involves mapping the inputs that we
want in a given sequence to the actual "inputs" to the rock at a
particular time (or alternatively, if one doesn't allow arbitrary
mappings for inputs, simply assuming that the rock gets a certain
set of inputs of the right kind).  Precisely the same construction
goes through: he can set up his state-definitions so that the rock
goes through just the right state-transitions in response to the
given inputs.

The problem, of course, is that it is only sensitive in the right way
to those *actual* inputs.  If it were a true FSA, it would have to be
the case that if a different set of inputs had come in, it would
have made different appropriate state-transitions.  That's what Putnam's
construction doesn't handle, and that's why I say that it comes
down to counterfactuals.  His construal of an FSA may be OK, but
his requirements for what it takes to implement an FSA are far too
weak.

-- 
Dave Chalmers                            (dave@cogsci.indiana.edu)      
Center for Research on Concepts and Cognition, Indiana University.
"It is not the least charm of a theory that it is refutable."


