From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!uunet!psinntp!scylla!daryl Wed Feb 26 12:54:39 EST 1992
Article 4022 of comp.ai.philosophy:
Path: newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!uunet!psinntp!scylla!daryl
>From: daryl@oracorp.com
Newsgroups: comp.ai.philosophy
Subject: Re: Reference (was re: Multiple Personality Disorder and Strong AI)
Message-ID: <1992Feb25.182526.12698@oracorp.com>
Date: 25 Feb 92 18:25:26 GMT
Article-I.D.: oracorp.1992Feb25.182526.12698
Organization: ORA Corporation
Lines: 58

Christopher Green writes (in response to Stanley Friesen):

CG:

   1. Brains cause minds. Now, of course, that's really too crude....
   2. Syntax is not sufficient for semantics....a conceptual truth....
   3. Computer programs are entirely defined by their formal, or syntactical
      structure....true by definition [of a computer program]
   4. Minds have mental contents; specifically, they have semantic contents....
      just an obvious fact about the way minds work....

  Conclusion 4. For any artefact that we might build which had mental states
              equivalent to human mental states, the implementation
              of a computer program would not by itself be sufficient.
              Rather, the artefact would have to have powers equivalent to 
              the powers of the human brain.

SF:
    As I have already stated, I question assumptions 2 and 3.

CG: 

> I can't conceive of what you object to in 3. It doesn't need
> evidence.  It's utterly analytic. Learning to program, even a little,
> should convince you.

I think you (like Searle before you) are equivocating on the use of
the phrase "programs are purely syntactic". A program is certainly a
syntactic object; it is a formal description, or specification, of a
class of systems (the "implementations" of the program). Learning to
program involves (at least in part) learning the syntax of a
programming language. However, the fact that a program is syntactic
(as is any formal description) does not mean that the implementations
of the program are purely syntactic. This kind of reasoning is akin
to: "Hydrogen is described by the Schrodinger equation. The
Schrodinger equation is mere marks on a piece of paper. Therefore,
hydrogen is marks on pieces of paper."

Now, let's turn to the other sense in which it is commonly claimed
that "programs are purely syntactic". *Computers* don't directly
manipulate real objects; it cannot, for instance, examine a real
hamburger, it can only examine a syntactic internal representation of
a hamburger. In this sense, computers are called syntactic because (a)
they only deal with representations, not with the real things, and (b)
the representations are discrete and digital. These points are
certainly true, but they make the claim that "Syntactic means no
semantics" very dubious. *Human brains* don't directly manipulate the
real things, either, they only manipulate internal representations, so
in that sense, they are just as syntactic as computers. The only point
left of Searle's syllogism--and a point that Steven Harnad seems
impressed by--is that computers, by dealing with *digital*
representations can never grasp the analog world. This seems pretty
dubious reasoning to me; certainly it is not the analytic truth that
Searle claimed for his point 3.

Daryl McCullough
ORA Corp.
Ithaca, NY


