Re: Rép : The Meaning of Life

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Wed, 24 Jan 2007 16:40:05 +0100

Le 23-janv.-07, à 06:17, Stathis Papaioannou a écrit :

>
>>> Searle's theory is that consciousness is a result of actual brain
>>> activity, not Turing emulable.
>>
>> Nooooo....... True: Searle's theory is that consciousness is a result
>> of brain activity, but nowhere does Searle pretend that brain is not
>> turing emulable. He just implicitly assume there is a notion of
>> actuality that no simulation can render, but does not address the
>> question of emulability. Then Searle is known for confusing level of
>> description (this I can make much more precise with the Fi and Wi, or
>> with the very important difference between computability (emulability)
>> and provability.
>
> Searle seems to accept that CT implies the brain is Turing emulable,
> but he
> does not believe that such an emulation would capture consciousness any
> more than a simulation of a thunderstorm will make you wet. Thus, a
> computer
> that could pass the Turing Test would be a zombie.


Yes. It confirms my point. And Searle is coherent, he has to refer to a
notion of "physically real" for his non-computationalism to proceed.
He may be right. Now his naturalistic explanation of consciousness
seems rather ad hoc.
But all what I say is that IF comp is correct, we have to abandon
physicalism.


> Searle is not a computationalist - does not believe in strong AI - but
> he does
> believe in weak AI. Penrose does not believe in weak AI either.

Yes. In that way Searle is "not even wrong".

<snip: see my preceding post to you>


> If there are more arbitrary sequences than third person computations,
> how
> does it follow that arbitrary sequences are not computations?


I guess I miss something (or you miss your statement?). Is it not
obvious that "if there are more arbitrary sequences than third person
computations, then some (even most) arbitrary sequences are not
computations".

Let us define what is a computable infinite sequence. A sequence is
computable if there is a program (a machine) which generates
specifically the elements of that sequence in the right order, and
nothing else. The set of programs is enumerable, but by Cantor theorem
the set of *all* sequences is not enumerable. So the set of computable
sequences is almost negligible compared to the arbitrary one.

Does it mean there is no program capable of generating a non computable
sequence?

Not at all. A universal dovetailer generates all the infinite
sequences. The computable one, (that is, those nameable by special
purpose, specific, program) and the non computable one (how? by
generating them all).

I give another example of the same subtlety. One day a computer
scientist told me that it was impossible to write a program of n bits
capable of generating an incompressible finite sequence or string of
length m with m far greater than n. I challenge him.
Of course, what is true is that there is no program of n bit capable of
generating that m bits incompressible string, AND ONLY, SPECIFICALLY,
THAT STRING.
But it is really easy to write a little program capable of generating
that incompressible string by letting him generate ALL strings: the
program COUNT is enough.

I think this *is* the main line of the *everything* list, or a
miniature version of it if you want.

Now, when you run the UD, as far as you keep the discourse in the third
person mode, everything remains enumerable, even in the limit.
But from the first person point of view, a priori the uncountable
stories, indeed generated by the UD, take precedence on the computable
one: thus the continua of white rabbits. This results from the lack of
any possibility from the first person point of view to locate herself
into UD*. Somehow the first person belongs to 2^aleph_zero histories at
the start.

A similar "explosion of stories" appears with quantum mechanics, except
that here the physicist as an easy answer: white rabbits and Potter
universe are eliminated through phase randomization (apparently).

I am not satisfied by this answer if only because my motivation is to
understand where that quantum comes from.

Is complex randomization of histories the only way to force normal
nature into the shorter path?

Well, my point is that if we take comp seriously, we have to justify
the absence of rabbits from computer science. In case too much white
rabbits remains, comp would be false, and this would be an argument in
favor of materialism. But, when you interview a universal machine on
this question you can realize at least that this question is far from
being settled.



Hope you don't mind I continue to comment your post tomorrow,


Bruno




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


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Received on Wed Jan 24 2007 - 10:40:28 PST

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