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Article 2395 of comp.ai.philosophy:
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>From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Searle's response to silicon brain?
Message-ID: <1991Dec24.054745.16805@bronze.ucs.indiana.edu>
Organization: Indiana University
References: <BSIMON.91Dec19071828@elvis.stsci.edu> <1991Dec21.015200.14397@bronze.ucs.indiana.edu> <41010@dime.cs.umass.edu>
Date: Tue, 24 Dec 91 05:47:45 GMT
Lines: 41

In article <41010@dime.cs.umass.edu> orourke@sophia.smith.edu (Joseph O'Rourke) writes:

>This is an adequate answer unless Bernie Simon means to focus on
>the chemical interface between the silicon neurons and the biological
>tissue with which it communicates in some fashion.  Here simulation
>will not suffice.  This is especially an issue in David Chalmers' 
>version of the thought experiment where the neurons are replaced 
>one at a time.  

This is a complex matter, but basically I don't see any real problem
with the idea that insofar as the non-neural biological tissue plays a
causal role, we can simulate it.  Presumably we'll divide it up into
little chunks and simulate those one at a time, keeping track of
those properties that are relevant to causation: monitoring inputs
to the region (e.g. chemical changes at the boundary), updating
our simulation of the internal state accordingly, and producing
via some kind of transducer the appropriate outputs (again including
chemical changes).  The sensitivity of neurons to the surrounding
tissue can be simulated similarly.

This begins to seem a little forced, partly because it's a lot easier
to imagine the transduction of electrical input/outputs than that of
chemical input/outputs, but I don't see a difference in principle --
it will just be far harder to achieve in practice.

>	One could imagine tiny chemical reservoirs with computer-
>controlled release mechanisms (not unlike fuel injection control
>in automobiles), which would enable a silicon neuron to release
>an appropriate amount of e.g. acetlycholine at just the right times.
>Such chemical release would be needed only at the interface between
>silicon and biological tissue; the silicon/silicon interface could
>be simulated as Chalmers suggests.

That's another way we could do it, but it would have less force
against Searle, as we'd still be relying on specific physiochemical
properties in an essential way.

-- 
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."


