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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Causes and Reasons
Message-ID: <1992Jan10.011118.26218@bronze.ucs.indiana.edu>
Organization: Indiana University
References: <1991Dec24.020441.8340@bronze.ucs.indiana.edu> <1991Dec24.014716.6901@husc3.harvard.edu> <5918@skye.ed.ac.uk>
Date: Fri, 10 Jan 92 01:11:18 GMT
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In article <5918@skye.ed.ac.uk> jeff@aiai.UUCP (Jeff Dalton) writes:

>It may help me to understand this if you can tell me how many
>different causal structures count as an implementation?  Well,
>not just how many -- what is the range of possibility.  Are
>all of the implementations the right structrue for thinking?

I spelt this out, at least for the FSA case, in an earlier message.
And yes, all of the implementations think, given the right program.

>I'm not even sure that all correct implementations have the right
>causal structure, since a given program can have a wide range of
>implementations, with a wide range of causal structures.  (Some
>might use ICs, other beads and string; there are different compilers
>that produce different object code; etc.)

There can be a lot of differences, but there will be certain causal
properties that will be shared between everyu implementation of a
given program; think of the simple FSA program "S1->S2, S2->S3,
S3->S1" for example.

>If all of these are the right causal structure for thinking, it
>seems to me that they must be "right" at a fairly abstract level,
>which again suggests functionalism.

Of course this suggests functionalism (supervenient functionalism),
as I've acknowledged a number of times.  The original context for this
discussion was to examine the role of programs and implementations,
given that mentality is supervenient on causal structure.

>Or, instead of considering "implementation", we might consider
>a program a (functional) description of a causal structure.
>But Searle would still be right if it matter in what kind of
>physical system the causal structure was realized.

Of course, if Searle is right about the relevance of certain
physico-chemical properties, then all this is wrong.

>There's a huge step from state transitions to C programs, since
>a C program could be implemented by so many different patterns
>of state-transitions.

But there will be certain invariants in causal structure, and they're
the relevant properties.  e.g. consider a simulation of a neural
network in C, with a variable representing the activation of each unit.
Then in any implementation there will be a physical state (or property)
corresponding to each variable, and these physical states will have the
appropriate causal relations between them.

-- 
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."


