From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Dualism
Organization: Indiana University
Date: Wed, 30 Sep 1992 01:09:04 GMT

In article <1992Sep29.231258.1999@meteor.wisc.edu> tobis@meteor.wisc.edu (Michael Tobis) writes:

>>  So consciousness is at least nomically supervenient on the
>>brain (i.e. subject to the laws of nature, it's necessary that
>>identical brain states give rise to identical conscious states).
>
>Um, but my dictionary defines "supervenient" as "coming or occuring as
>something additional, extraneous, or unexpected". That doesn't seem to
>correspond to "necessary" to me. (It's Webster's 7th Collegiate, btw)

Don't trust dictionary definitions in philosophical arguments.  In
the technical philosophical sense (which I outlined earlier in
this thread), a set of B-facts are supervenient on the A-facts
if any two individuals (or worlds) that agree in all their A-facts
necessarily agree in all their B-facts.  If the "necessity" here
is taken to be logical necessity, then the B-facts certainly aren't
anything extra -- e.g. facts about tallness are logically supervenient
on facts about molecular configuration, without that being anything
"extraneous" or "unexpected".  On the other hand, if the necessity
here is taken to be mere nomic necessity, then the supervenience
may well be something "additional, extraneous, or unexpected".  So
the term "supervenience" alone covers a multitude of sins; just what
is meant has to be specified more clearly by specifying the
relevant grade of necessity.  (Incidentally this often isn't done,
even by good philosophers, which can lead to no end of confusion.)

>>On the other hand, a zombie replica at least seems to be logically
>>possible.  If this is so, then consciousness is not logically
>>supervenient on the brain, but *only* nomically supervenient.
>>i.e., it arises from the brain in virtue of a nomic connection, or
>>a law of nature.
>
>Um, then how does your position differ from monism? If consciousness
>necessarily arises from the state of your brain, that sounds like
>the old "emergent property" handwaving to me. In what sense is this
>consistent with dualism? Do you postulate "laws of nature" that are
>not included in what is normally called physics? Are you certain there
>are no zombies, for that matter?

Taking these questions backwards:

(1) Obviously I can't be certain there are no zombies, any more than
I can be certain that I'm not the only consscious being in the
universe (or that the world wasn't created 5 minutes ago, or whatever),
but I nevertheless find it very implausible.  The universe would be a
strange and arbitrary place if that were so.

(2) Yes, if this brand of dualism is correct, then there are laws of
nature over and above those included in or implied by the laws of
physics.  (Specifically, the laws connecting physical/functional
states to experiential states.)

(3) I agree that invocation of "emergent properties" in this context
is usually handwaving, as it's usually an attempt to have one's
materialist cake and eat it too.  Either the emergent properties are
implied by the base properties, in which case one has materialism, or
they are not, in which case one has dualism.  My view is clearly
dualism, as I hold that the facts about consciousness are facts over
and above (not implied by) the physical facts.  (There could be a
universe physically identical to ours that differs in its conscious
states.)

(4) I suppose this is compatible with some sort of "monism", but
certainly not with a materialist kind.  Personally, I am hopeful
for some kind of information-based monism, where both the physical
and the experiential are seen to be different aspects of information.

-- 
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."