Re: MGA 3

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Tue, 2 Dec 2008 19:48:19 +0100

Hi Günther,


On 01 Dec 2008, at 22:53, Günther Greindl wrote:

>
> Hi Bruno,
>
>>> but no! Then we wouldn't have a substrate anymore.
>> Oh( That is not true! We still have the projector and the film. We
>> can
>> project the movie in the air or directly in your eyes.
>
> Ok I see now where our intuitions differ (always the problem with
> thought experiment) - but maybe we can clear this up and see where it
> leads...


OK.



>
>
>> it is really something people have to meditate. I could have conclude
>> in the absurdity of MAT (with MEC) at MGA 2. It is hard for me to
>> take
>> people seriously when they argue that the consciousness of Alice
>> supervenes on a movie of its brain activity. There is no causality,
>> nor computations, during the *projection* of the movie.
>
> If that is how you see MAT (you require causality) - then I would also
> agree -> MGA 2 shows absurdity.

Well I require at least a minimum of physical causality to implement
physically the computational "causality" (which incarnates platonic
relation existing among numbers).

MAT presupposes anything primitively material and causal of course.
Remember that I am using Materialism and physicalism (and naturalsim)
as synonymous, because the argument is very general. The (naïve) idea
is that the brain *does* compute something when you dream, for
example, and that it is the physical causality which is responsible
for the implementation of the computation.

>
>
>> Alice's
>> experience is related to ALL computations going through those states,
>> not to descriptions of those states which can been made and collected
>> in other histories. Locally it makes sense to ascribe *that*
>> consciousness when you have the mean to interpret (through some
>> universal machine) her computational states.
>
> That is already part of your theory (UDA and all) (as I understand
> it),
> but not included already in COMP or in MAT.


Not at all. This could be confusing for those who don't know UDA. Once
MEC+MAT is shown to be incompatible, we then chose MEC and thus
abandon MAT.
(why? just for not going out of the range of my working hypothesis, ok)

With MEC, there is no more physical supervenience thesis, on the kind
compatible with MEC. But we keep MEC, so we have to continue to
related consciousness with the computation, right? We do no more have
a notion of physical computation, so we attach consciousness to the
computation itself, LIKE it has already been done in the UDA, except
that we don't need no more to run the UD.



>
>
>> [Consciousness of (x,t)] is never [physical states] at (x,t)
>
> For me, the above expresses the essence of (naive) MAT -> let's call
> it
> NMAT.
>
> So, clearly:
> NMAT: [Consciousness of (x,t)] supervenes on [physical states] at
> (x,t)
>
> And on physical states only! Not on the causal relations of these
> states
> (block universe view).


You are perhaps taking me too much literally here. It is just
difficult, lengthy and confusing to make a precise definition of the
physical supervenience which would work for the different views of the
universe.
The physical supervenience thesis just says that 1) there is a
physical universe, 2) it can compute, and consciousness requires some
special local computations made *in* that universe.



>
>
> Your argument goes like this:
>> it is:
>> [Consciousness of (x,t)] is always all computational states (in the
>> UD
>> °) corresponding to that experience. (It is an indexical view of
>> reality).
>
> And I share it IF we can show that MAT+MEC is inconsistent. But I am
> not
> convinced yet.
>
> For me, the essence of MEC (COMP) is this:
>
> COMP: there is a level at which a person can be substituted at a
> digital
> level (we don't have to go down to "infinity"), and where this digital
> description is enough to reconsitute this person elsewhere and
> elsewhen,
> independent of substrate.
>
>
> NMAT additionally requires that the substrate for COMP be some
> "mysterious" substance, and not only a platonic relation.


Not so mysterious. It just seems to require some particular
computations. The "physical" one. People are used to think about it in
term of waves or particles, or field, geometrical dynamical object.
They believe those are particulars (which become mysterious only with
comp, but a priori with Mat they are rather "natural");



>
>
> My intuition tells me this can't be -> we have to drop either MEC or
> NMAT.
>
> But MGA 3, when dropping the boolean gates, violates NMAT, because:
> NMAT: [Consciousness of (x,t)] supervenes on [physical states] at
> (x,t)
>
> And the physical states relevant where the _states of the boolean
> graph_
> (the movie projector was just the lucky cosmic ray).
>
> Do you have different definition for MAT? Do you require causal
> dynamics
> for MAT?


MAT is very general, but indeed it requires the minimum amount of
causality so that we can implement a computation in the physical
world, if not I don't see how we could talk on physical supervenience.



>
>
> The problem with NMAT as I define it raises the issue as in the Putnam
> paper -> does every rock implement every finite state-automaton?
>
> Chalmers makes the move to implementation, so introduces causal
> dynamics.
>
> So, sophisticated MAT would probably be:
> SMAT: [Consciousness of (x,t)] supervenes on [physical states] at
> (x,t)
> over a timespan delta(t) _if_ sufficiently complex causal dynamics are
> at work during this timespan relating the physical states.


No this is MAT. But with COMP, if it happens that a boolean gates or
neurons *personal history" has to be taken into account, by definition
of MEC, it means we don't have chose correctly the level of
substitution.


>
>
>
> Then I would say: MGA 2 (already) shows that SMAT+MEC are not
> compatible.

All right then!



> No need for MGA 3.

OK.


>
>
> For NMAT+MEC (which is problematic for other reasons) MGA 3 is not
> convincing.

I think I have miss something.

>
>
> Would you agree with this?


I am not sure I understand the NMAT.
What MGA is supposed to do is to eliminate the hypothesis of the
concrete UD in the step seven of UDA. Do you think it does, or not
(yet)?

Best,

Bruno



http://iridia.ulb.ac.be/~marchal/




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Received on Tue Dec 02 2008 - 13:48:27 PST

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