Le 27-août-06, à 23:17, David Nyman wrote to Peter (1Z) :
>> 1Z: But you don't really address the existence question. You just >> loosely >> assume it is the >> same thing as truth. > > Could I appeal to Bruno at this juncture to address this point > directly?! At several places in our own dialogues, Bruno, you've > implied that your 'number theology' was an 'as if' postulate, because > (if I've understood) you are concerned to see how much can be explained > by starting from this particular set of assumptions. I don't believe > that you are claiming they are 'true' in an exclusive sense, rather > that they are enlightening. Is this a correct interpretation of your > position, or is there further nuance? As a scientist, or if you prefer as a "willing to be a consistent scientist" (you never know), I would say that *all* theories are third person discourses which have to be taken with an "as if" proviso. Even the grandmother physics (with propositions like 'objects fall', or 'the sun rise in the morning', etc.) is like that. Even our unconscious theories that we have probably inherited from our ancestors are like that. Of course, given a theory, we can harbor doubts about it, and we can harbor those doubts differentially, that is more or less doubts on some part of it. "My" theory is a digital version of the very old mechanist theory, saying that we are sort of natural machine. It is already explained by Nagarjuna in the "Milinda's Questions" for example, or by Plato in some place, and it has been developed by Descartes concerning animals (and perhaps concerning humans too in some hidden way, if you take the context of Descartes epoch). I make that digital version more precise so as to be able to drive precise conclusions. I have called in this list that more precise version: COMP (but I called it digital mechanism in some places). Note that what you call "number theology" belongs to the conclusion of comp (I don't assume it). The precise comp version is given by a) the "yes doctor" act of faith YD b) Church (Hypo) Thesis CT c) Arithmetical Realism hypothesis AR Now I can imagine "a)" to be false. In three ways actually: For example I say yes to the doctor but the digital reconstitution of me remains inanimate, or, I say yes to the doctor, and the digital reconstitution is a zombie, or I say yes to the doctor, and the reconstitution is alive but is not me. This I can logically conceived, and that would make "a)" wrong. Note that in the lobian interview we do not need anymore the "yes doctor", except for giving a general sense to the *goal* of the interview. It is much harder for me to conceive that Church thesis could be false, but this is due to more than many years of reflection on it. I am not so much impress by the empirical evidence (all attempt to define computable function lead to the same class of function, despite completely different definitions and motivations), but I am infinitely impressed by the closure for the diagonalization of the class of partial computable functions. This is a quite convincing argument for CT, as I try to explain periodically on this list. Still I can "logically" doubt about CT. It is enough that someone comes up with a function and a way to explain me how to compute and a proof that the function cannot be programmed in Java (say), and CT would be refuted. I would say that this is unlikely. Now, it is still much more harder for me to doubt about AR. It is about AR that I often say that I would have the feeling to lie to myself in case I would pretend harboring doubt about it. AR just says that elementary number theoretical statements (including existential one) are true or false in a way which does not depend on me. Actually I am even using a weaker version of AR, in the sense that for the ontic part of the theory, I need only the independent truth of the formula with the shape ExP(x), i.e. "it exist a number verifying the property P", where P is an easily verifiable statement (like being prime, being odd, etc.). I don't need universal (with the "for all" quantifier) independent truth, only the simpler formula among the existential one. (of course I don't believe at all in Peter Jones heavy form of magical platonism). I have also never met someone doubting about AR, although I met regularly people who pretend to doubt AR, but like Peter, they put in it things which I don't put in it at all. Somehow, to believe in NON-AR you have to believe in the possibility that there is a proposition of arithmetic, stating the existence of a number having some verifiable property, which truth value is capable of changing according to the fact that you are alive or not. You need to make a stronger and much weirder ontological commitment to get it. Some people ask me: but if AR is so obvious, why do you postulate it? I postulate it for reason of completeness, but also because I am aware of contradicting 1500 years of implicit theological aristotelian belief, and so I need to be quite explicit about what I assume. Although very simple to believe, AR does play a key role, if not *the* key role in the UDA proof. AR eventually provides the whole comp ontology, although it has nothing to do with any commitment with a substantial reality. Hope this helps, Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. 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