Re: implementations

From: Marchal <>
Date: Sat Jul 3 10:05:03 1999

Jacques M Mallah wrote:

>On 1 xxx -1, Marchal wrote:
>> Jacques M Mallah wrote:
>> > Chalmers includes a
>> >reference to Maudlin's paper and obviously does not think it ruled out
>> >physical computationalism.
>> > BTW Chalmers' own proposed solution in that paper is
>> >unsatisfactory, and he admits it, hence the need for proposals such as
>> >mine.
>> And you admit (if I read correctly your URL) that your proposal (for
>> the implementation problem) is also still unsatisfactory.
>> There is indeed an "implementation" problem.
> I think the idea of my proposal is basically correct, but it needs
>refinement. It should be made more precise and possible to state more
>simply and must be tested with a barrage of proposed implementations that
>must be declared "true" or "false". But in research it is to be expected
>that it may take several tries (and maybe several people) to get something
>right. I'm being cautious because I've already tried and rejected a
>number of ideas that seemed good at the time.
> Currently it has not been proven that the problem can be solved or
>that my proposal does so, and it also has not been proven that this is not
>the case. It may well be impossible to either find a solution or to prove
>that one does not exist.
>> My feeling (let us say) is that
>> this problem is *fatal* for the physical computationalist (like you ;
>> BTW thanks for this nice expression).
>> What I JUST show in my thesis is that IF the mathematical (arithmetical
>> is enough)
>> computationalist solve the "implementation problem" (your term) THEN
>> she will justify the origin of the appearance of the physical laws and
>> solve the mind body problem.
> I don't see much difference is this respect between the 'math' and
>'physics' versions. You still want a 'math' computation that simulates
>the universe to implement a brain computation, so you need the same kind
>of solution to the implementation problem. Without this you have almost
>no chance to get the right predictions but the universe is less complex
>than the brain.

I have no doubt we agree on some key points.

Unlike Dennett you are aware of a "matter problem" (through the
interpretation of QM),
Unlike Penrose you are aware of a "mind problem", including the fact that
the link
between computation and physical activity is not obvious.
And I agree gladly with you when you say that an interpretation of QM
needs a theory of mind.

Nevertheless I am not quite sure we have the *same kind* of
implementation problem.
Roughly speaking you try to find criteria for linking consciousness to
physical instantiation of computations.

What I say, is that if we take the computationalist hypothesis seriously

- 1) your implementation problem is necessarily insoluble ...

- 2) ... untill you understand that with comp there is just no physical
activities at all, only relative believes in *physical activities* by
kind of *mean* machines (and the means are taken on the whole set of
infinite computationnal histories, ...

- 3) ... so that there is no other choices than to justify the (relative)
beliefs, by machines, in physical laws. This could be done through
a sort of theoretical psychology (or theology, cf the immortality point),
which, thanks to comp, is essentially theoretical computer science,
including classical information theory.
We should explain for exemple, why there is no appearance of white flying
rabbits ...

I am aware of saying something quite radical here. For exemple most people
in the quantum computing community are thinking, following Landauer, that
the very existence of quantum computers show that information is
physical. This is because they belief from the start in a *physical
and I guess because they have not thought enough on the mind body problem

In fact I tend to believe that the classical Church's thesis CT
entails the falsity of what David Deutsch called the "Church Turing
principle" (CTP). This means that the constraints of the classical
computationnalism (with CT) are enough for explaining the appearance
(in the machine's mind) of "physical computation" apparently violating
Church's thesis.

We agree on important points which are unfortunately not understood
by many people, but we disagree on important points too.
We disagree on the immortality question but we disagree also on what I
would like to call the necessary reversal that comp implies.

If I am correct,
it will be hard to maintain that physics is necessarily the fundamental
science (an Aristotelian Dogma).
With comp the fundamental science is not physics, but, let us say, the
psychology of the Universal Turing Machines. What Garlanter and John
Myhill call "exact psychology".
Physical realities are inside-(relative)-views by machines belonging
to a vast collection of -implementation independent- sharable dreams
(computationnal histories).

A real attempt to derive, in this spirit, physics from psychology is
given in the chapter 5 of my thesis
But I don't think it is worth to engage on that godelian road before
people acknowledges the *reversal* between physics and psychology, which
nothing to do a priori whith the incompleteness phenomenon, but is a
prelude to some interesting (new) interpretations.

Received on Sat Jul 03 1999 - 10:05:03 PDT

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