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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Newsgroups: comp.ai.philosophy,sci.philosophy.tech
Subject: Re: A rock implements every FSA
Message-ID: <1992Mar26.205453.27114@bronze.ucs.indiana.edu>
Date: 26 Mar 92 20:54:53 GMT
References: <92Mar18.182726est.14357@neat.cs.toronto.edu> <1992Mar19.000544.22634@bronze.ucs.indiana.edu> <9203261657.AA12526@ucbvax.Berkeley.EDU>
Organization: Indiana University
Lines: 73

In article <9203261657.AA12526@ucbvax.Berkeley.EDU> kap@vnet.ibm.com writes:

>Note that when physically implementing an abstract automaton, the
>physical representation of input and output data formats is entirely
>arbitrary.

A number of people seem to be saying things like this, so I should
note that Putnam himself is quite explicit on this point (p. 124):

  The inputs and outputs have certain constrained realizations,
  or at least their realizations must be of certain constrained
  kinds depending on our purposes; usually we are not allowed
  to simply *pick* physical states to serve as their realizations,
  as we are allowed to do with the so-called "logical states" of
  the automaton.

Of course it's not entirely clear just what these constraints are,
but I suggest that at the very least the inputs really have to
be *inputs*: i.e. they have to supervene on a spatially distinct
region from internal states of the automaton.  That's enough to
defeat a few of the more bizarre attempts at pan-implementationalism
that have been seen around here.

>The theory of counterfactuals is very controversial; counter-identical
>statements such as you propose are the among the most problematic
>topics in the theory.  If Functionalism is to be saved only by appealing
>to unspecified future developments in the theory of counterfactuals,
>it may be a very long time before the functionalists can answer such
>basic questions as "which objects instantiate automaton X?"

As I've said a number of times, we don't need any sophisticated
theory, such as a possible-worlds similarity metric, to evaluate the
simple counterfactuals involved in the definition of implementation,
as the relevant antecedents are fully specified.

>It was bad enough when Functionalism was the only game in town.  Now
>we're supposed to stop playing Functionalism and play Counterfactuals
>instead?   Yuck.  There has to be a better way.

Some people seem to be running a mile at any mention of the term
"counterfactual".  There's really no problem.  Functionalism has
*always* been concerned with these.  Or even look at its
predecessor, behaviourism.  Did Ryle say that mental states were
fully determined by actual behaviour?  Of course not.  He said
that mental states were determined by behavioural *dispositions*,
i.e. how the system *would* behave, or *would have* behaved, in
certain circumstances.  There are your counterfactuals.

Perhaps I should take Joseph O'Rourke's advice and drop the term
"counterfactual", even though it's correct.  "Strong conditionals"
will do instead.  Any vaguely functionalist theory will require
a system to satisfy certain conditionals, and it's obvious
that these can't just be weak material conditionals, made vacuously
true by the falsity of the antecedents in the actual run of things.
Rather, they carry some modal force, i.e. if the antecedent *were*
true then the consequent *would* come about.  The "counterfactuals"
in the Putnam case are just these modal conditionals, whose truth
is being evaluated after the fact -- i.e. if the antecedent *had*
occurred, then the consequent *would have* come about.  But
obviously after-the-fact evaluation doesn't make any difference to
the truth of these conditionals.  And if anyone wants to say that
no strong conditional has a determinate truth-value, they have
a lot of arguing to do.  Most of science will have to be redone,
for a start.

Most of the Putnam-style refutations come about by implicitly
interpreting these conditionals as simple material conditionals,
which is just silly.

-- 
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."


