Re: RE : Re: Discussion of the MUH

From: Bruno Marchal <>
Date: Mon, 10 Mar 2008 12:43:02 +0100

Le 08-mars-08, à 21:09, George Levy a écrit :

> Hi Brian
> As Russell said, we have been discussing this topic for at least a
> decade. We all respect each other. I am sure that Bruno did not mean
> harm when he made his comment.

Actually I was replying, not even to Brian. But thanks.

> You bring up an interesting question: the relationship between Fuzzy
> logic and the MUH and you state that Fuzzy logic is a superset of
> deterministic logic. Isn't true that Fuzzy Logic can be implemented by
> means of a Turing Machine? Since a Turing Machine is purely
> deterministic it means that Fuzzy logic is actually a subset of logic.
> Hence the ad hoc introduction of Fuzzy logic may be unnecessary in the
> context of MUH.
> I don't think that the indeterminacy that we are considering here is
> fundamental or derives from an axiomatic approach. It is rather a
> consequence of living in many worlds simultaneously.

This is the key point. Tegmark believes that the physical universe
could be a mathematical structure among others, which I can believe
too. But with the coomputationalist hypothesis or its many weakenings,
we have to take into account all mathematical structures supporting the
self aware entities, to derive that particular mathematical structure.
So we just cannot postulate a theory like "SWE", we have to derive it
from a sum on all (sufficiently rich) mathematical structures. We just
cannot consistently invoke a notion of existence of a "physical
universe". This gives a clue why we believe or could believe in such a
physical universe.

> When "I" make a
> measurement, a number of "I"'s make(s) a measurements. The result of
> the
> measurement that each "I" perceive(s) defines the world where the "I"
> actually am (is). As you can see English is not rich enough to talk
> about "I" in the third person or in the plural.
> If there is a need for Fuzzy Logic, it would have to be a kind of logic
> adapted to deal with the MUH. I don't know enough to say if there is
> such a logic.

This puts light on the reason why the "explicitation" of comp (or its
weakenings) is useful. The logic, in this case, has to be derived (by
the UDA) from the sum invoked above. When the math are done we do find
indeed a sort of quantum logic (ref in my url). It is an open problem
if this logic is a fuzzy quantum logic. Evidences add up to think it
could be a form of quantum credibility, instead of the "usual" quantum
probability theory. This is related to the fact that we get the modal B
logic (the "Brouwersche system") *without* the rule of necessitation.
Much works remain, of course.


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Received on Mon Mar 10 2008 - 07:43:38 PDT

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