On Nov 20, 2008, at 10:52 AM, Bruno Marchal wrote:
> I am afraid you are already too much suspect of the contradictory
> nature of MEC+MAT.
> Take the reasoning has a game. Try to keep both MEC and MAT, the game
> consists in showing the more clearly as possible what will go wrong.
I understand what you're saying, and I accept the rules of the game. I
*am* trying to keep both MEC and MAT. But it seems as though we differ
on how we understand MEC and MAT, because in my understanding,
mechanist-materialists should say that Bruno's Lucky Alice is not
conscious (for the same reason that Telmo's Lucky Alice is not
conscious).
> You mean the ALICE of Telmo's solution of MGA 1bis, I guess. The
> original Alice, well I mean the one in MGA 1, is functionally
> identical at the right level of description (actually she has already
> digital brain). The physical instantiation of a computation is
> completely realized. No neurons can "know" that the info (correct and
> at the right places) does not come from the relevant neurons, but from
> a lucky beam.
I agree that the neurons don't "know" or "care" where their inputs are
coming from. They just get their inputs, perform their computations,
and send their outputs. But when it comes to the functional, physical
behavior of Alice's whole brain, the mechanist-materialist is
certainly allowed (indeed, forced) to talk about where each neuron's
input is coming from. That's a part of the computational picture.
I see the point that you're making. Each neuron receives some input,
performs some computation, and then produces some output. We're
imagining that every neuron has been disconnected from its inputs, but
that cosmic rays have luckily produced the exact same input that the
previously connected neurons would have produced. You're arguing that
since every neuron is performing the exact same computations that it
would have performed anyway, the two situations are computationally
identical.
But I don't think that's correct. I think that plain old, garden
variety mechanism-materialism has an easy way of saying that Lucky
Alice's brain, viewed as a whole system, is not performing the same
computations that fully-functioning Alice's brain is. None of the
neurons in Lucky Alice's brain are even causally connected to each
other. That's a pretty big computational difference!
I am arguing, in essence, that for the mechanist-materialist,
"causality" is an important aspect of computation and consciousness.
Maybe your goal is to show that there's something deeply wrong with
that idea, or with the idea of "causality" itself. But we're supposed
to be starting from a foundation of MEC and MAT.
Are you saying that the mechanist-materialist *does* say that Lucky
Alice is conscious, or only that the mechanist-materialist *should*
say it? Because if you're saying the latter, then I'm "playing the
game" better than you are! I'm pretty sure that Dennett (and the other
mechanist-materialists I've read) would say that Lucky Alice is not
conscious, and for them, they have a perfectly straightforward way of
explaining what they *mean* when they say that she's not conscious.
They mean (among other things) that the actions of her neurons are not
being affected at all by the paper lying in front of her on the table,
or the ball flying at her head. For Dennett, it's practically a non-
sequitur to say that she's conscious of a ball that's not affecting
her brain.
> But the physical difference does not play a role.
It depends on what you mean by "play a role". You're right that the
physical difference (very luckily) didn't change what the neurons did.
It just so happens that the neurons did exactly what they were going
to do anyway. But the *cause* of why the neurons did what they did is
totally different. The action of each individual neuron was caused by
cosmic rays rather than by neighboring neurons. You seem to be asking,
"Why should this difference play any role in whether or not Alice was
conscious?" But for the mechanist-materialist, the difference is
primary. Those kinds of causal connections are a fundamental part of
what they *mean* when they say that something is conscious.
> If you invoke it,
> how could you accept saying yes to a doctor, who introduce bigger
> difference?
Do you mean the "teleportation doctor", who makes a copy of me,
destroys me, and then reconstructs me somewhere else using the copied
information? That case is not problematic in the way that Lucky Alice
is, because there is an unbroken causal chain between the "new" me and
the "old" me. What's problematic about Lucky Alice is the fact that
her ducking out of the way of the ball (the movements of her eyes, the
look of surprise, etc.) has nothing to do with the ball, and yet
somehow she's still supposed to be conscious of the ball.
A much closer analogy to Lucky Alice would be if the doctor
accidentally destroys me without making the copy, turns on the
receiving teleporter in desperation, and then the exact copy that
would have appeared anyway steps out, because (luckily!) cosmic rays
hit the receiver's mechanisms in just the right way. I actually find
this thought experiment more persuasive than Lucky Alice (although I'm
sure some will argue that they're identical). At the very least, the
mechanist-materialist has to say that the resulting Lucky Kory is
conscious. I think it's also clear that Lucky Kory's consciousness
must be exactly what it would have been if the teleportation had
worked correctly. This does in fact lead me to feel that maybe
causality shouldn't have any bearing on consciousness after all.
However, the materialist-mechanist still has some grounds to say that
there's something interestingly different about Lucky Kory than
Original Kory. It is a physical fact of the matter that Lucky Kory is
not causally connected to Pre-Teleportation Kory. When someone asks
Lucky Kory, "Why do you tie your shoes that way?", and Lucky Kory
says, "Because of something I learned when I was ten years old", Lucky
Kory's statement is quite literally false. Lucky Kory ties his shoes
that way because of some cosmic rays. I actually don't know what the
standard mechanist-materialist way of viewing this situation is. But
it does seem to suggest that maybe breaks in the causal chain
shouldn't affect consciousness after all.
And of course, we can turn the screws in the usual way. If we can do
Lucky Teleportation once, we can do it once a day, and then once an
hour, and then once a second, and so on, until eventually we just have
nothing but random numbers, and if those random numbers happen to look
like Kory, aren't they just as conscious as Lucky Kory was? But this
doesn't convince me (yet) that Lucky Alice should be viewed as
conscious after all. It just convinces me (again) that there's
something weird about the mechanistic-materialist view of
consciousness. Or about the materialist's view of "causality".
>> But the mechanist-materialist can (and must) claim that
>> Lucky Alice did not in fact respond to the ball at all.
>
> Consciously or privately?
Physically! By the definition of the thought experiment, it is a
physical fact that no neuron in Alice's head responded to the ball (in
the indirect way that they normally would have if she were wired
correctly). Whether or not she had a conscious experience of a ball is
a different question.
>> 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".
>
> Careful: such kind of causality needs ... MAT.
Yes, of course. But we're *supposed* to be considering the question in
the context of MAT.
> But at that level, a
> neurophysiologist looking in the detail would see the neurons doing
> their job. Only, he will also see, some neurons breaking down, and
> then being fixed, not by an internal biological fixing mechanism (like
> it occurs all the time in biological system, but by a lucky beam, but
> despite this, and thanks to this, the brain of Alice (MGA 1) does the
> entire normal usual work.
What do you mean by "fixed"? If the cosmic rays "fix" the neurons so
that they are able to respond to the input of their neighboring
neurons as they're supposed to, then I've misunderstood the thought
experiment. But if you mean that the cosmic rays "fix" the neurons by
(very luckily) sending them the same inputs that they would have
received from their neighboring neurons, then I don't agree that the
neurophysiologist looking at the details would conclude that the
neurons are doing their job, or that the brain of Alice MGA 1 is doing
its entire normal usual work. He would conclude that the brain is not
physically reacting to the pencil or the paper or the ball at all. For
a mechanist, how can a person be aware of a ball if not a single
neuron in her head is physically reacting to that ball?
>> 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.
>
> Alice MGA 1 can be said to be aware in the roiginal mechanist sense.
> When she thought "Oh the math problem is easy", she trigged the right
> memories in her brain, with the correct physical activity, even if
> just luckily in that case.
Memory is notoriously confusing, so lets keep talking about the ball.
What can a mechanist possibly mean by saying that Lucky Alice was
aware of the ball? By the definition of the thought experiment (unless
I've misunderstood it), every single neuron in Lucky Alice's brain is
being triggered by cosmic rays rather than by neighboring neurons. Not
a single action of any neuron (and therefore, not a single movement of
her body) has anything to do with the movement of the ball. All we can
say is that the neurons are (very improbably) being triggered in the
exact same way that they *would* have been triggered if they were
wired up correctly, and they were actually responding (indirectly) to
the light on her retinas, etc.
So what would it mean to say that, nevertheless, Lucky Alice is aware
of the ball? The only sense I can make of this is that, since each
individual neuron is doing exactly what it would have done anyway, the
same "experience" (qualia, whatever) results (or supervenes, or
whatever). But that's exactly the view of consciousness that Dennett
(the archetypical mechanist-materialist) has spent a lifetime arguing
against. For him, that would be a very magical view of consciousness.
For him, the "experience" of being aware of the ball, "deciding" to
duck, etc., is simply what it feels like to be a collection of neurons
responding to that ball. When he says, "This collection of neurons is
aware of that ball", he is saying, by definition, that that ball is
having causal effects on those neurons. (And not just the causal
effects that any physical object has on any nearby physical object.)
> And things will even be more confusing after MGA 2, but that's the
> goal. MEC + MAT should give a contradiction, we will extract some
> weirder and weirder proposition until the contradiction will be
> utterly clear. OK?
Of course I'm entirely on board with the spirit of your thought
experiment. You think MECH and MAT implies that Lucky Alice is
conscious, but I don't think it does. I'm not sure how important that
difference is. It seems substantial. But I can also predict where
you're going with your thought experiment, and it's the exact same
place I go. So by all means, continue on to MGA 2, and we'll see what
happens.
-- Kory
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Received on Fri Nov 21 2008 - 04:45:50 PST