re: delayed reply

From: Marchal <>
Date: Thu Mar 11 01:27:11 1999

Gilles Henry:
>I still have difficulties in accepting the idea that the reality "is" a
>mathematical abstraction. The mathematics as we know them are mental
>concepts than can be applied to modelize *approximately* what we observe
>from the world. There is no example so far of a really "exact" theory, free
>from any unconsistency and unaccuracy. Modern epistemology is seeing the
>evolution of science as an always improving approximation of reality. So
>you can as well defend the idea that mathematics will *never* give a
>complete description of reality.

Indeed. Actually, since Goedel'sincompleteness result, we even know that
mathematics will *never* give a complete description of arithmetical reality.
My feeling is that you confuse mathematical reality and mathematical tools.
Facing mathematical reality, the mathematician confront difficulties
very similar to those facing the physicist.

>I don't want you to mistake what I am saying. I am not saying that doing
>physics is better than doing mathematics or computer science. i am just
>saying that each field has its own domain of relevance ; although at some
>precise interfaces, they can mutually enrich, one should be cautious in
>applying them to domains for which they were not built.

Sure. The problem here consist in finding the relation between mathematical
reality and physical reality. You can believe there is a physical universe,
and that mathematics are *mental* tools build by high mammifers for strugling
with the physical universe. This is a respectable position.
What I say is that such a respectable position is incompatible with the
hypothesis of computationalisme. I am *just* saying that IF we can survive
with a digital brain, THEN physical reality is NECESSARILY part of
arithmetical reality "viewed from inside". This gives us a new
*space* (the space of computationnal histories) which gives clues on the
logical origin of the (machine-belief in) physical laws.

>>Have you follow the PE-omega experience ?
>I missed that, could you explain it ? (I'm afraid it is not an experiment
>in my sense!)

I guess it is not an experiment in your sense, indeed. It is a thought
experiment. According to my reading of James Robert Brown's book on thought
experiments() it is a simultaneously destructive and constructive platonic
thought experiment. It is destructive because it shows the inconcistency of some set of *traditionnal beliefs* (basically Mechanism and some very weak form of Materialism). It is constructive because it constructs a new frame for solving old problems, from the applicability of math to physics to the mind-body problem, ...
You can find it in a preeceding post to James Higgo or Juergen Schmidhuber.
I suggest you to use the "find" tools (on "PE-omega") in the ESCRIBE archive
It is also in my Phd thesis, pp. 5-14.
Schmidhuber tells us he doesn't follow it. So I have propose him to present it by little steps. STEP1 is just my "definition" of computationnalism:

          STEP1: COMP => I can survive with a digital brain.

Do you agree ?

> ... Schmidhuber's programms, for example, could most
>simply interpreted like the generation of classical worlds where "1" means
>the presence of a classical particle and 0 an absence. There is nothing
>wrong logically...just that you cannot make good physical laws with this

I agree with Schmidhuber and James Higgo (and Wei Dai (?), ...) ONTOLOGICAL explanation: roughly speaking I agree that the "great programmer" is the simplest explanation for everything.
What those people seem not to understand is the formidable EPISTEMOLOGICAL problems which arise with such an ontology. My UD-argument (or PE-omega experiment) is build to show the inevitability of these epistemological


() BROWN James Robert, 1991, The Laboratory of the Mind, Routledge, paperback edition 1993, London.
Received on Thu Mar 11 1999 - 01:27:11 PST

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