From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Dualism
Organization: Indiana University
Date: Sun, 13 Sep 1992 17:24:27 GMT

In article <1992Sep13.000522.17474@galois.mit.edu> tycchow@riesz.mit.edu (Timothy Y. Chow) writes:

>Let me see if I've got this right.  Many of us have speculated at some time
>or another whether or not the color green "looks the same" to other people
>as it does to us.  Maybe other people, when they see a red cape, see what I
>see when I see green, but call it red.

Sure.  Some people have tried to deny that this is a coherent speculation,
but that seems to be a consequence of a rigid verificationism.  The
possibility certainly seems to be meaningful.

>Consider the Turing test.  Suppose a machine passes the Turing test.  Is
>it thereby conscious?  In principle it seems that a very simple but
>extremely detailed computer program---namely, one that has a vast number
>of "if-then" statements covering every possible stimulus that it might
>encounter---could pass the Turing test, but would leave many uncertain
>about calling it "conscious."
>
>The above are the intuitions underlying Dave Chalmers' argument, I think.

Well, my arguments about dualism haven't got much to do with the giant
lookup (if-then) table, one way or the other.  It applies to systems
of any functional organization.  Even once we know all the facts
about that functional organization, the fact of the system's consciousness
or otherwise won't follow logically.

On the other hand, there may be very good inductive reasons to think
that such a machine is conscious.  For instance, I think a machine
with functional organization very similar to mine will probably be
conscious.  On the other hand, the giant lookup-table probably won't
be conscious.  But in any case, this is just inductive speculation
about the way the world works, and the way the laws connecting
consciousness to the physical works.  It's not a matter of logical
necessitation.  Consciousness doesn't seem to be logically
necessitated by any set of physical facts, and that's all the
dualist requires.

>A complete catalogue of physical facts about vision might still leave us
>wondering whether or not other people's visual experiences are the "same"
>as ours.

Well, again there would be very good reasons for believing that their
experiences were the same, but there's still a logical gap, in a way
that there wouldn't for wondering about whether another person was
alive, for instance.

>Similarly, even if no human being can devise a test that will
>distinguish between Dave Chalmers and the if-then monster, and even if we
>have a complete listing of the if-then monster, we might still be unsure
>about whether the if-then monster is conscious, even though it assures us
>that it is.
>
>	Us: Are you conscious?
>   Monster: [encountering "IF STIMULUS('ARE YOU CONSCIOUS?') THEN
>              RESPONSE('OF COURSE---WHAT DO YOU THINK?')"]  Of course---
>              what do you think?

Again, I'm not sure why you're concentrating on the giant lookup-table,
which is more relevant to the contingent question of which physical
systems consciousness *in fact* arises from, rather than the
question of which systems consciousness *must* arise from (by logical
necessity).

>In response to this one can simply dismiss talk of "consciousness" and
>"visual experience" as vague terms; questions like "Is the machine
>conscious?" or "Are other people's visual experiences the same as mine?"
>don't make precise sense until "consciousness" and "visual experience" are
>defined behavioristically or in terms of physical facts.  And of course
>once we have such a definition we can answer the question by referring to
>our catalogue of physical facts.  This is the physicalist approach.

One cuold try to do that, but it would to injustice to the manifest
phenomena.  The reality of consciousness and visual experience is
entirely clear to us, and isn't vague at all.  All that's vague
are attempts to pin these things down in terms of other concepts.
Certainly, to *define* consciousness in terms of behaviour is entirely
to beg the question, as you point out below.

>One might object that our experiences of redness, solidity, and other
>conscious experiences are about as basic as we can get, and arguably even
>the term "physical facts" is ultimately defined in terms of such
>fundamental experiences.  To define these experiences in terms of physical
>facts would be circular.  At least it requires a strong argument to say
>that the experience of redness is really nothing more than a bunch of
>exceedingly complicated and intricate physical facts.

Right.  Just conceivably it might *turn out* that redness is nothing more
than a bunch of physical facts; but to *define* redness that way at
the outset would simply be changing the subject.  One might as well
define redness as the behaviour of falling bodies.  We have an
explanation of the behaviour of falling bodies, so therefore we have
an explanation of redness, voila!

-- 
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."
Newsgroups: sci.philosophy.tech