On Nov 18, 2008, at 11:52 AM, Bruno Marchal wrote:
> The last question (of MGA 1) is: was Alice, in this case, a zombie
> during the exam?
Of course, my personal answer would take into account the fact that I
already have a problem with the materialist's idea of "matter". But I
think we're supposed to be considering the question in the context of
mechanism and materialism. So I'll ask, what should a mechanist-
materialist say about the state of Alice's consciousness during the
exam?
Maybe I'm jumping ahead, but I think this thought experiment creates a
dilemma for the mechanist-materialist (which I think is Bruno's
point). In contrast to many of the other responses in this thread, I
don't think the mechanist-materialist should believe that Alice is
conscious in the case when every gate has stopped functioning (but
cosmic rays are randomly causing them to flip in the exact same way
that they would have flipped if they were functioning). Alice is in
that case functionally identical to a random-number generator. It
shouldn't matter at all whether these cosmic rays are striking the
broken gates in her head, or if the gates in her head are completely
inert and the rays are striking the neurons in (say) her arms and her
spinal chord, still causing her body to behave exactly as it would
have without the breakdown. I agree with Telmo Menezes that the
mechanist-materialist shouldn't view Alice as conscious in the latter
case. But I don't think it's any different than the former case.
It sounds like many people are under the impression that mechanism-
materialism, with it's rejection of zombies, is committed to the view
that Lucky Alice must be conscious, because she's behaviorally
indistinguishable from the Alice with the correctly-functioning brain.
But, in the sense that matters, Lucky Alice is *not* behaviorally
indistinguishable from fully-functional Alice. For the mechanist-
materialist, everything physical counts as "behavior". And there is a
clear physical difference between the two Alices, which would be
physically discoverable by a nearby scientist with the proper
instruments.
Lets imagine that, during the time that Alice's brain is broken but
"luckily" acting as though it wasn't due to cosmic rays, someone
throws a ball at Alice's head, and she ("luckily") ducks out of the
way. The mechanist-materialist may be happy to agree that she did
indeed "duck out of the way", since that's just a description of what
her body did. But the mechanist-materialist can (and must) claim that
Lucky Alice did not in fact respond to the ball at all. And that
statement can be translated into pure physics-talk. The movements of
Alice's body in this case are being caused by the cosmic rays. They
are causally disconnected from the movements of the ball (except in
the incidental way that the ball might be having some causal effect on
the cosmic rays). When Alice's brain is working properly, her act of
ducking *is* causally connected to the movement of the ball. And this
kind of causal connection is an important part of what the mechanist-
materialist means by "consciousness".
Dennett is able to - and in fact must - say that Alice is not
conscious when all of her brain-gates are broken but very luckily
being flipped by cosmic rays. When Dennett says that someone is
conscious, he is referring precisely to these behavioral competences
that can be described in physical terms. He means that this collection
of physical stuff we call Alice really is responding to her immediate
environment (like the ball), observing things, collecting data, etc.
In that very objective sense, Lucky Alice is not responding to the
ball at all. She's not conscious by Dennett's physicalist definition
of consciousness. But she's also not a zombie, because she is behaving
differently than fully-functional Alice. You just have to be able to
have the proper instruments to know it.
If you still think that Dennett would claim that Lucky Alice is a
zombie, take a look at this quote from
http://ase.tufts.edu/cogstud/papers/zombic.htm
: "Just remember, by definition, a zombie behaves indistinguishably
from a conscious being–in all possible tests, including not only
answers to questions [as in the Turing test] but psychophysical tests,
neurophysiological tests–all tests that any 'third-person' science can
devise." Lucky Alice does *not* behave indistinguishably from a
conscious being in all possible tests. The proper third-person test
examining her logic gates would show that she is not responding to her
immediate environment at all. Dennett should claim that she's a non-
conscious non-zombie.
Nevertheless, I think Bruno's thought experiment causes a problem for
the mechanist-materialist, as it is supposed to. If we believe that
the fully-functional Alice is conscious and the random-gate-brain
Alice is not conscious, what happens when we start turning Alice's
functioning brain-gates one-at-a-time into random brain gates (and
they luckily keep flipping the way they would have)? Alice's deep
behavior changes - she gradually stops responding to her environment,
although her outward behavior makes it look like she still does - but
clearly there's nothing within Alice "noticing" the change. We
certainly can't imagine (as Searle wants to) that Alice is internally
feeling her consciousness slip away, but is powerless to cry out, etc.
It's tempting to say that this argument simply shows us that Lucky
Alice must be conscious after all, but that's just the other horn of
the dilemma. The mechanist-materialist can only talk about
consciousness in computational / physical terms. For Dennett, if you
say that Alice is "aware", you must be able to translate this into
mechanistic terms. And I can't see any mechanistic sense in which
Lucky Alice can be said to be "aware" of anything.
I prefer to just say that Bruno's thought experiment shows that
there's something wrong with mechanism-materialism, but it's not
obvious (yet) what the solution is.
-- Kory
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Received on Thu Nov 20 2008 - 02:23:09 PST