Re: MGA 3

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Wed, 3 Dec 2008 10:08:53 +0100

Hi Abram,

On 02 Dec 2008, at 20:33, Abram Demski wrote:

>
> Bruno,
>
> I am a bit confused. To me, you said
>
>> Or, you are weakening the physical supervenience
>> thesis by appeal to a notion of causality which seems to me a bit
>> magical, and contrary to the local functionalism of the
>> computationalist.
>
> This seems to say that the version of MAT that MGA is targeted at does
> not include causal requirements.


MAT is the usual idea that there is a physical world described through
physical laws. Those capture physical causality, generally under the
form of differential equations. If there were no causality in physics,
the very notion of physical supervenience would not make sense. Nor MEC
+MAT, at the start. Sorry if I have been unclear, but I was
criticizing only the *magical* causality which is necessary for
holding both the physical supervenience thesis and the mechanist
hypothesis, like attribution of prescience to the neurons (in MGA 1),
or attributing a computational role in inert Material.



>
>
> To Günther, you said:
>
>>> 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.
>
> Does the MAT you are talking about include causal requirements or not?


Of course.


>
>
> About your other questions--
>
>> OK, so now you have to disagree with MGA 1. No problem. But would you
>> still say "yes" to the mechanist doctor? I don't see how, because
>> now
>> you appeal to something rather magic like influence in real time of
>> inactive material.
>
> So long as that "inert" material preserves the correct
> counterfactuals, everything is fine. The only reason things seem
> strange with olympized Alice is because *normally* we do not know in
> advance which path cause and effect will take for something as
> intricate as a conscious entity. The air bags in a car are "inert" in
> the same way-- many cars never get in a crash, so the air bags remain
> unused. But since we don't know that ahead of time, we want the air
> bags. Similarly, when talking to the mechanist doctor, I will not be
> convinced that a recording will suffice...


Me too. But that remark is out of the context of the argument. If I
want an artificial brain (MEC) I expect it to handle the
counterfactuals, because indeed we don't know things in advance. But
in the context of the proof we were in a situation where we did know
the things in advance. Suppose that my doctor discovers in my brain
some hardware build for managing my behavior only in front of
dinosaurs, like old unused subroutine being only relic of the past,
then it seems to me that the doctor, in the spirit of mechanist
functionalism can decide of dropping those subroutine for building me
a cheaper artificial brain. And that is all we need for the argument
for going through. Consciousness relies on the computation which
always kept the right counterfactuals, and never on their relative
implementations which will only change their relative measures.



>
>
>> The real question I have to ask to you, Günther and others is this
>> one: does your new supervenience thesis forced the UD to be
>> physically executed in a "real" universe to get the UDA conclusion?
>
> Yes.

Then it seems to me you are relying on some magical causality attached
to a magical notion of matter. I don't understand how you can still
say yes to a doctor with such a notion of mechanism. See above. I
would no more even trust a Darwinian brain.


>
>
>> Does MGA, even just as a refutation of "naïve mat" eliminate the use
>> of the concrete UD in UDA?
>
> No.
>
> (By the way, I have read UDA now, but have refrained from posting a
> commentary since there has been a great deal of discussion about it on
> this list and I could just be repeating the comments of others...)


Then you can read the answers I have given to the others. It seems to
me UDA(1..7) does no more pose any problem, except for those who have
decided to not understand, or believes "religioulsy" in matter and
comp. In public forum group you always end up discussing with those
who like cutting the hairs.


>
>
> Also: Günther mentioned "SMAT", which actually sounds like the "CMAT"
> I proposed... so I'll refer to it as SMAT from now on.


I am sorry if I have been unclear, but MAT is taken in a very large
sense. MAT is the belief in a physical universe obeying physical laws,
be it quantum, classical, or whatever. Actually, for a
computationalist (especially after UDA+MGA), MAT seems to be just a
way to single out one special computations above the others.

Kim Jones has convinced me to explain UDA, and the general idea, a new
time. It could be an opportunity to let us known your commentaries. To
be sure, some mathematicians get more easily the point when I
introduce the arithmetical translation of the UDA. You can study it in
my papers or wait I explain this also on the list, or search the list
archive for the explanation of the AUDA that I have already given. Of
course mathematicians are a minority here and I try not to exaggerate
with the list patience. What is subtle in MGA is a bit subtler in
AUDA, too, but then it relies at least on non controversial facts in
Mathematical Logic, which are unfortunately not well known nor well
taught. Except the logicians, logic is not very well known even by
mathematicians.

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




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Received on Wed Dec 03 2008 - 04:09:03 PST

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