From: chalmers@bronze.ucs.indiana.edu (David Chalmers)
Subject: Re: Dualism
Organization: Indiana University
Date: Mon, 28 Sep 1992 05:30:26 GMT

In article <1992Sep23.050550.25320@galois.mit.edu> tycchow@riesz.mit.edu (Timothy Y. Chow) writes:

>First, Chalmers' claim that a complete physics is possible and that it will
>probably look very much like what we understand now sounds alarm bells in my
>head because it sounds VERY much like what physicists were saying at the end
>of the 19th century, and they were drastically wrong.  However, this is a
>small point since Amazing New Advances in Physics don't seem to be the real
>issue here.

Well, "very much like" is relative, of course.  I don't doubt that
physics is going to change a whole lot.  But the kind of change
required for physics to suddenly entail qualia would be a change far,
far more radical than any change to date.  The "revolutions" of
relativity and quantum mechanics were mild by comparison.

>Secondly, Chalmers claims that the breakdown of causality in quantum
>mechanics is a "small" one.  Under any sort of remotely reductionist view,
>any breakdown at the quantum level translates into a breakdown at all higher
>levels.  (Classic example: a bomb detonated by a Geiger counter.)  However,
>"causality" doesn't seem to be the right word here; physicists still talk
>about causality---what the Copenhagenists deny is determinism.  But again I
>think this is a side issue.

I said the causal gaps in QM are small.  That doesn't mean they can't
have large consequences (especially with chaotic processes amplifying
quantum indeterminacies).  People like Eccles have relied on this
for the "mind" to do its causal work in little, appropriate nudges;
still, most people find it very implausible that these nudges can be
what make the vast, systematic difference between "mindless" and
"mindful" behaviour.  (For a start, it would imply that the
"indeterminacy" in QM was systematic, not random; secondly, given the
practical unpredictability of chaotic amplifications, this view would
suppose that the "mind" has an amazing ability to invert complex
evolutionary equations.)

>Both of the following appear coherent:
>
>(*) Every even integer greater than two is the sum of two primes.
>(*') Some even integer greater than two is not the sum of two primes.
>
>Now A asserts (*) and B asserts (*').  On whom does the burden of proof lie?

Neither of these seems obviously coherent (i.e. logically possible) to
me.  That question is entirely up in the air.  Mathematical questions
are something of a special case, given that (a) there is no middle
ground between necessity and impossibility; and (b) there is no
question of exhibiting or ruling out particular possible worlds that
make a proposition true, unlike the case with these other propositions
that concern world-varying subject matters.

>It seems that Chalmers must further claim that the alternative, namely that
>zombie replicas cannot exist, seems incoherent.  In fact Chalmers appears to
>hold this, claiming something like: the nature of the concepts of physical
>fact and consciousness appear to be completely unrelated and hence to claim
>that one is entailed by the other is incoherent.

Not at all.  I simply say that these two propositions ("zombie replicas
cannot exist"; "one is entailed by the other") are false, that's all.
To say that they are incoherent would be to make a second-order
modal judgment of a kind I'm unconcerned with.  (Maybe if modal
statements are false, they're impossible, but that's not an issue here.)

>Against this Randall Holmes seems to hold that consciousness just IS a
>physical fact---perhaps by definition?  For Holmes, then, what Chalmers
>claims to be incoherent is virtually tautologous.
>
>Perhaps the issue is not just one about logical impossibility, as I
>suggested earlier, but about explanation.  Randall Holmes thinks that
>being able to give a physical/functional explanation of why human beings
>act the way they do and say the things they do about consciousness is
>enough to "explain" consciousness.  Dave Chalmers looks at his conscious
>experience but does not think that such a physical/functional explanation
>really "explains" it.  Hence he is not willing to identify mental facts
>with physical facts, whereas Randall Holmes has no such hesitation.

That's about right.  Certainly if one makes it a *definitional* truth
that consciousness is physical, then one establishes physicalism, at
the cost of changing the subject from consciousness to something else.
Similarly, if one makes it a definition truth that consciousness is
whatever is responsible for our claims about consciousness, then one
does the same thing.  But sadly, neither of these is a remotely
adequate "definition" of consciousness; they simply trivialize the
subject matter.

-- 
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