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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Causes and Reasons
Message-ID: <1992Jan19.231218.16873@bronze.ucs.indiana.edu>
Organization: Indiana University
References: <1992Jan14.004439.7502@husc3.harvard.edu> <1992Jan14.201839.28881@bronze.ucs.indiana.edu> <1992Jan19.164650.7804@husc3.harvard.edu>
Date: Sun, 19 Jan 92 23:12:18 GMT
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In article <1992Jan19.164650.7804@husc3.harvard.edu> zeleny@zariski.harvard.edu (Mikhail Zeleny) writes:

>Incidentally, what do you mean by `more or less
>identical'? are you perchance suggesting that physical states are "sorta
>supervenient" on computational states, i.e. that the universe is, _au
>fond_, nothing but a big computer?  For this is, in effect, a direct
>consequence of your claims that, given correct implementation, program
>structure formalizes physical causal structure.

The point is simply that two physical objects that share all their
computational states will, as a matter of contingent fact, be
physically identical or very similar.  This follows from considerations
about e.g. the atomic composition of matter, and the fact that
different atoms have different computational structure, so that at the
very least two objects identical in all their computational states must
be composed of type-identical sets of atoms; the similarity between the
objects can be further constraioned by considering the causal relations
that must hold between the atoms.  There's probably room for a little
difference, e.g. atoms that are positioned slightly differently in a way
that doesn't affect any computational state.  Certainly there is no
claim that "the universe is nothing but a big computer".

>Good grief! now you want an isomorphism between mental states and a subset
>of computational states; but on the assumption of "sorta supervenience", we
>get back to "sorta functionalism", which has been sorta refuted by Putnam.
>No, the real moral of this story is that you shouldn't put your premisses
>in your opponent's mouth.

Not at all.  Strong supervenience, i.e. the claim that for a given mental
state M there exists a computational state C such that implementing C
is sufficient (though not necessary) for M, is not affected by Putnam's
arguments.

>You keep saying that, and I keep explaining that you are wrong: anecessary
>connection is a matter of ontology, and is necessary, but not sufficient
>for the existence of a nomological connection.  For instance, the necessary
>connection may obtain between events of such complexity that it cant be
>characterized in a finite language.  This situation sure looks anomalous to
>me.  Are you really prepared to maintain as an incorrigible, irrefutable
>article of faith that the universe cannot have any regularities that we
>would be intrinsically unable to characterize by finite means?

Nomologically necessary regularities, on my conception thereof and on
that of many others, need not be finitely characterizable.  It seems to me
that this is an uninteresting terminological difference about the status of
nomological necessity, no longer concerning any substantive matter.

>Correction: it will have two computational states, which may correspond to
>any number of physical states (this is where intensionality comes in).
>Unless, that is, you really think that the world is a computer, and that
>you can discover its program while remaining within it.

It doesn't matter how many physical states may correspond, as long as there
exist at least two with the appropriate causal connection.

-- 
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."


