From: Hal Finney (hal@rain.org)
Date: Sat Jun 14 1997 - 10:17:55 MDT
Damien Broderick, <damien@ariel.ucs.unimelb.edu.au>, writes:
> I've just finished reading Dave Chalmer's book The Conscious Mind, which
> left me wondering exactly *what* he *is* saying... but I think you've got
> it turned around, Hal. Chalmers' argument for the singular and unreductive
> character of consciousness is based firmly on the feasibility of
> counterfactual possible worlds which are replete with zombies. These
> critters are identical with us down the quantal level, but lack the
> supervenience of consciousness and hence lack `experience' and `qualia' -
> even though they claim to have them (being perfect behavioural emulations
> of conscious people). Certainly Dave argues against *us* being zombies -
> he rejects the John Clark model, in other words - but his whole argument
> hangs on the modal possibility that a zombie world *is* intelligible. I
> don't think it is, in rather the way I don't think it's genuinely possible
> to ask the hoary old question `why is there anything rather than nothing?'
> I don't think we *can* conceive of the absence of literally *everything*,
> just of the absence of certain structures. The rest is just words,
> free-floating and (in such cases) delusive signifiers.
I have not read Chalmers' book, but I have read several of the papers on
his web site and I've seen discussion on comp.ai.philosophy.
I agree with you that Chalmers' notion that a zombie world is "logically"
possible is questionable. He eventually rejects the possibility, as you
say. But he is willing to entertain it as a hypothetical starting point.
The question of whether zombies are logically impossible versus merely
physically impossible is a bit too subtle for my grasp of philosophy.
It seems to me that the kinds of arguments philosophers make are basically
logical and don't really depend on the nature of the physical world.
I suppose they are not logical in the strict sense of axiomatic deduction;
even in the fading qualia example Chalmers admits that it is conceivable
that consciousness would behave in that bizarre and counter-intuitive way,
where people are unable to describe their fading consciousness.
Is it this loophole in his argument that forces him to leave open the
possibility of zombies? In that case I would say that the problem
is that his argument is not airtight, rather than that it is based on
the nature of the physical world. The conclusion I draw is that it is
*very likely* that zombies are logically impossible, not that they are
logically possible but physically impossible.
Hal
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