Hi Bruno,

My sixth sens says you're talking about something important :) but I don't
get it.
It could have been of much more interest, if you could elaborate, or provide
us with some references for each part of your argument.(Beginning from the
'OBVIOUS IMPORTANT QUESTION' it becomes vague for me)


On 5/16/07, Bruno Marchal <[EMAIL PROTECTED]> wrote:
>
>
> Hi,
>
> I take the opportunity that the list is calm to send a first
> approximation of a possibly extendable post which addresses the
> beginning of the background needed for the interview of the universal
> machine on the physical laws.
> It also addresses some point relevant for discussing the link "formal
> system" <======> "Computation" as in Tegmark diagram page 18 of his
> paper "the mathematical universe" (cf a post by Mark Geddes).
>
> Although schematic, it could already help me if you can list the points
> for which you would like examples or more technical details, or just
> explanations. You can also ask for *less* technical details like an
> explanation in (pure) english, perhaps.
>
> I am building again from Robinson Arithmetic, but I could have use the
> combinators or any logical description of what a universal machine (a
> computer) can do. The adavantage of using Robinson Arithmetic (or its
> "little" variant) is that provability in Robinson Arithmetic
> corresponds to universal computability, but not of universal
> provability (which does not exist).
>
>
> I am perhaps on the verge of not being able to explain the sequel in
> informal term, but I keep hope that non expert, but computer-open
> minded people, can learn and help me to be clearer or more pedagogical,
> without having us to study thoroughly mathematical logic.
> Tell me perhaps if you don't understand what I call "Searle's error" in
> the comp setting below.
>
>
>                                           ***
>
>
> 0) historical background
>
> ARISTOTLE: reality = what you see
> PLATO: what you see = shadows of shadows of shadows of shadows of  ....
> what perhaps could be.
>                And would that be? nobody can say, but everybody can get
> glimpses by looking inward, even  (universal) machines.
>
> Twentieth century: two creative bombs:
>
>        - The Universal Machine (talks bits): UM (Babbage, Post, Turing,
> Church, Suze, von Neumann, ...)
>        - The other universal machine (talks qubit):  QUM (Feynman,
> Deutsch, Kitaev, Freedman, ...)
>
> Comp = Milinda-Descartes Mechanism in a digital version. = (also) "YES
> DOCTOR" + CHURCH'S THESIS. (I suppress the arithmetical realism,
> because it is implicit in CHURCH'S THESIS).
>
>
> UDA: a reasoning which shows that if comp is correct then the physical
> laws have to be derived by a measure on states (the measure being made
> up through their computational histories).
>
> Subgoal: extract QUM from UM's self-observation.
>
> Link with everything-list: search for the "observer moments" and the
> relevant structure operating on them (not yet solved).
>
>
>                                           ***
>
>
> 1) The ontic theory of everything: LRA (Little Robinson Arithmetic),
>
>      CLASSICAL LOGIC (first order predicate logic axioms and inference
> rules)
>      AXIOMS OF SUCCESSION
>      AXIOMS OF ADDITION
>      AXIOMS OF MULTIPLICATION
>
>
> That's all. It is the "Schroedinger" equation of the comp-everything!
> The reason is that LRA is already as powerful as a universal machine.
> LRA proves all verifiable sentences with the shape ExP(x), with P(x)
> decidable. It is equivalent with the universal dovetailer.
>
> Now we have to do with LRA  what Everett has done with QM. Embed the
> observer in the ontic reality.
> For this we have to "modelize" the observer/knower/thinker.
>
>
>
>
>                                           ***
>
>
>
> 2) The epistemic theory, or the generic observer theory: PA (the lobian
> machine I will interview).
>
>      CLASSICAL LOGIC (first order predicate logic axioms and inference
> rules)
>      AXIOMS OF SUCCESSION
>      AXIOMS OF ADDITION
>      AXIOMS OF MULTIPLICATION
>      AXIOMS OF INDUCTION
>
> Note: the observer extends the ontic reality! It extends it by its
> beliefs in the induction axioms. They are as many as they are formula
> F(x), and they have the shape:
>
> [F(0) & Ax(F(x) -> F(x+1))]  -> AxF(x)
>
>
>
>
>                                           ***
>
>
>
>
>
> OBVIOUS IMPORTANT QUESTION: How to interview PA when we dispose
> ontologically only of LRA?
>
> NOT OBVIOUS SOLUTION: just try to obviate the fundamental SEARLE ERROR
> (cf Mind's I, Hofstadter -Dennett describe it well) in front of the LRA
> theorems.
>
>
> I explain: Searle's goal consisted in arguing against mechanism, that
> is arguing we are not machine, and in particular that a simulator is
> not the real thing. He accepts the idea that in principle a program can
> simulate a chinese speaker. Knowing the program, Searles accepts he can
> simulate it, and this without understanding chinese. He concludes that
> we have to distinguish between speaking chinese and simulating speaking
> chinese.
>
> True! but with comp you have to distinguish between the simulated
> chinese speaker and the simulator of the chinese speaker! By being able
> to simulate the chinese speaker, Searle can have a conversation with
> the chinese speaker (well assuming that the chinese speaker can talk
> english, or that Searle knows chinese).
>
> This is particularly important in our setting. LRA has the power of a
> universal turing machine, so it has universal computability power, and
> can act as a universal simulator. In particular LRA can simulate PA,
> and any recursively enumerable theory/machine. But compute or simulate
> are not similar to believing or proving (or talking in some genuine
> personal way).
>
> LRA provides a view of computability as a very particular and quasi
> debilitating case of provability. LRA can prove almost only the true
> Sigma1 sentences (which is enough to run the UD). For example, LRA
> cannot prove (about its ontic reality or intended interpretation) that
> Ax (x + y = y + x). PA can. PA is already a sort of Ramananujan, a
> total genius compared to LRA, despite the fact that LRA is already
> universal for computation. For the notion of provability there is no
> universal notion. There are as many notion of provability than there
> are machines (human included).
>
> If you want,  LRA is gifted in proving the existence of number having
> verifiable property, and giving that PA can be defined, by Godel
> arithmetizability, in the language of LRA , although LRA has no opinion
> on the induction axioms (believed by PA), LRA can prove that PA proves
> this or that. And with strong-AI (that is Searle's weak Turing notion)
> LRA will prove "and Bruno says this or that". In this setting, Searle
> would confused LRA and PA, or LRA and Bruno.
>
> Now, I will not interview the brunos, but the PAs, as they have much
> less prejudices, if only that. By the "PAs" I mean the many recurring
> proofs by LRA that PA proves something (you can see that as the many
> simulations of PA by LRA). Well, the main advantage of interviewing PA
> is that anyone just a bit reasonable, believes in PA's beliefs.
>
> The PAs, are Löbian. In a nutshell, if LRA is indeed universal, PA is
> not only universal, but knows, in some weak sense, that she is
> universal.
> LRA has universal "existential provability" power about the verifiable
> propositions, but LRA has almost no universal "universal provability"
> power. LRA's talks go like this: oh a prime number! oh a proof by ZF
> that PA is consistent, oh ...", but LRA cannot prove the infinity of
> the primes, nor can LRA prove any reasonable result in number theory
> begining by a "Ax" (for all x) quantification. The induction axioms, in
> which PA believes, provide her with, not only a tremedous
> generalization power, but confers to PA the (modal-logically-viewed)
> maximal indepassable self-referential power (the one which are
> axiomatisable by the modal logics G, G*).
>
> Being universal LRA is under the joug of the incompleteness phenomenon.
> But this is not saying a lot given that we already know LRA's
> provability power are so weak. PA, being universal too, is obviously
> under that joug too, and that is more astonishing a priori, because, as
> I said, PA is already quite a genius with tremendous provability power.
> Now, by its powerful self-referential knowledge inherited by that
> provability power, knowing her universality, PA *knows* that she is
> under the joug of the incompleteness phenomenon.
>
> This makes PA, and all her correct (with respect to the usual model
> (N,+,x)) recursively enumerable extensions, incredibly modest!  (if not
> a bit naive). But it makes also PA "aware" of intensional distinctions,
> already described in the Theatetus, which provide then the arithmetical
> interpretations of Plotinus Hypostases. Including his "Matter"
> hypostases, making them comparable with quantum logic/quantum
> computations.
>
> OK, that last paragraph was quick. I have to explain more on logic
> (godelian, modal, but also the weak logics like intuitionistic logic or
> (mainly!) quantum logic, ...). Asap.
>
> Does this help a bit?
>
> Bruno
>
> http://iridia.ulb.ac.be/~marchal/
>
> >
>


-- 

Mohsen Ravanbakhsh,

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