Re: Discussion of the MUH

From: Bruno Marchal <>
Date: Wed, 5 Mar 2008 15:51:13 +0100

Le 05-mars-08, à 04:15, Brian Tenneson a écrit :

> I'm trying to strike up a discussion of the MUH but my discussion
> started at sci.logic and apparently, not many logicians are interested
> in Physics, or something... :P

Logicians are not interested in physics, and still less in metaphysics.
Bruno Poizat (a french logician) said (in its textbook on Model Theory)
that metaphysics is what logicians hate the most. I think this is just
a result of contingent historical facts ...
And physicists have been cooled down by the logicians reaction on
Penrose's use of Godel's theorem, so that they are a bit inhibited.
Even in the field of quantum computation, which has to bring back
eventually logicians and physicists around the table, big
misunderstandings still occur.

> Here is a link (two, actually) to the discussion. I don't know how to
> proceed, to discuss here or there. It does not matter to me.
> b0ed9baa707749ad/ef7752e4bcfc2631#ef7752e4bcfc2631

We have discussed this a lot on this list. I don't know if most people
have seen my point, but I can only sum up it here:

I think the physical world cannot be a mathematical structure among
others, but that physics-matter is more like a sort of border of
mathematics-mind. So the relation between math and physics are more
subtle than Tegmark seem to think. You can see this once you take
seriously the mind body problem (or the problem of relating machine's
first person talk and machine third person observations, provably so (I
think) once you assume some precise version of the computationalist
hypothesis. But Tegmark is right for its mathematicalist position.
Again: right with respect to the comp hyp.
To tackle the math of that "physical bord", I use the Godel Lob Solovay
modal logic of provability (known as G, or GL). More on this list or in
my url. You can make your point of course, or ask questions. Sometimes
but rarely, Tegmark does send a post. Try a specific question perhaps,
or consult the archive.


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Received on Wed Mar 05 2008 - 09:51:52 PST

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