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Article 1994 of comp.ai.philosophy:
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>From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Newsgroups: comp.ai.philosophy
Subject: Re: Searle, again
Message-ID: <5829@skye.ed.ac.uk>
Date: 9 Dec 91 22:09:39 GMT
References: <2127@ucl-cs.uucp> <91338.113617KELLYDK@QUCDN.QueensU.CA> <5796@skye.ed.ac.uk> <40333@dime.cs.umass.edu>
Reply-To: jeff@aiai.UUCP (Jeff Dalton)
Organization: AIAI, University of Edinburgh, Scotland
Lines: 39

In article <40333@dime.cs.umass.edu> orourke@sophia.smith.edu (Joseph O'Rourke) writes:
>Jeff Dalton writes:
>>                                                Searle points
>>out that the outputs of the sensors, the control instructions
>>for the manipulators, etc, are just more symbols that have to
>>-- somehow -- be given meanings.  So it's symbol manipulation
>>again.
>
>I think it is perhaps misleading to speak only of control "instructions."
>Eventually the control instructions are translated into control
>voltages.  It seems to me that depositing a "move arm" instruction
>into a register that is hardwired to a device that drives the arm
>motor with a voltage, exhibits just as much a causal link between
>the instruction and the arm movement, as does a mental intention
>causing the appropriate neuronal firings that retract a human arm
>muscle.

Ok.

>  The "move arm" instructions/symbols are given meaning by
>the design of the hardware, which seems to me analogous to the
>way the firing of certain neurons is "given meaning" by their
>connections to arm muscles.

This is on considerably shakier ground.  Are neuron firings
given meanings in the same way words are?  Things would be
a lot easier if we could uncontroversially bring in meanings
at some low level and find them in thermometers and thermostats;
but I think we still have to show how that kind of low-level
meaning eventually yields meanings of the other sort.

>	I fail to see Searle's claim that symbols have no causal
>power.

Does he claim this?  In any case, the "causal powers of the brain"
aren't those (or not just those) causal powers.  The important Searle
phrase here is, I think, "brains cause minds".

-- jeff


