On 7 June 2014 20:05, Bruno Marchal <marc...@ulb.ac.be> wrote: *At step 7, it is not in principle. Like in the preceding protocol, we just assume the existence of an infinite running of the UD in our infinite (then) space-time structure.*
*The proposition is that if that is the case, and don't see white rabbits, it means some computations are multiplied, and exploit (perhaps) the random oracle inherent in that multiplication. * OK, so the pedagogic purpose of step 7 is to persuade us that our experiences *could* be the consequence of the above, but it doesn't yet force that conclusion (because it could still be avoided in the way I have suggested). *The step 8 does not, and cannot, refute your point above, but it can explain how far it goes near a god-of-the-gap move, or a magic move. It is close to be proved, as to counteract to step 8 you are forced (in the transfinite) to provide a matter which is non Turing emulable, and non FPI recoverable. It looks like reifying a mystery to prevent a possible partial solution to a mystery. Someone might add that matter needs a "Gods" blessing, also. * Step 8, if I've understood it, shows that one can evacuate all traces of "computation" from a "primordial" physical instantiation (either by substituting a filmed record, under the particular contingencies of the movie graph, or by systematically substituting each of the "computational relations" by fortuitous physical events). This renders the ascription of "computation" to the physical events as entirely gratuitous. Hence what follows is either the abandonment of CTM, or alternatively the reversal consequence. The reversal could only then be avoided by an appeal, as you say, to some (presumably presently unknown) aspect of "primordial matter" that is not Turing emulable in principle (e.g. that required actual computational infinities). Even after such a move, any naturally motivated appeal to "computation" and its putative relation with consciousness is hardly any clearer than before. My own intuition, for what its worth, has always been that any appeal to "computation" on the assumption of "primordial matter" is somewhat suspect and ad hoc. ISTM that what is supposed to be "primordial" about a specific set of entities and their relations is precisely that they *exclusively* underlie (or more correctly, comprise) everything that is "really real". So the hierarchical structure of everything we observe thereafter - be it physical, chemical, biological, physiological, etc. - would be deemed to be underpinned, exclusively and exhaustively, by such a primordial substratum. The higher-order levels in the hierarchy could always, at least in principle, be reduced without loss to the primordial entities and their relations. They are, IOW, *re-descriptions* of primordial reality, not independent realities in themselves. If so, the problem in trying to add "computation" to such a hierarchy is that it must suffer the same fate - i.e. that of being reduced and eliminated as an ultimately supernumerary re-description of what is "really" just the primordial substratum. And consequently, if we attempt to attach consciousness to such a supernumerary re-description, it must inevitably be exposed to similar reduction and elimination. This is, I think, what the demonstrations in step 8 lay bare. By contrast, after the reversal, the primordial entities and relations are restricted to the natural numbers (or their equivalents) and their additive and multiplicative relations. It used to trouble me that the same arguments I have deployed above could seemingly equally be directed at this alternative "primordial substratum". That is, that whatever was deemed to "emerge" from arithmetic could in the final analysis always be reduced to it again without loss and hence ultimately eliminated as being independently real. But the critical difference here, compared with the starting point of "primordial matter", seems to be the natural emulation of computation and the universal machine in arithmetic. Their consequences in logic seem, at least in principle, to offer a route out of the reduction/elimination impasse by connecting an "outer structure" of basic arithmetical entities and relations with a much larger and more complex "internal reality" consisting of the modes of arithmetical truth. This latter reality is then no longer vulnerable in the same way to either reduction or elimination, though the task (substantially) remains, after a promising beginning, to connect it systematically and robustly with "observed reality". It occurred to me that the relation between such a substratum and its truth domain might be suggested, albeit rather imperfectly, by an analogy with something like an LCD screen. The idea is that an enormously large (infinite?) set of possible dramatic storylines can potentially be realised by a finite set (in this case) of "fundamental" entities and their relations (i.e. the pixels). Of course, the analogy immediately breaks down because, in the case of the screen, an external interpreter is necessary for any "dramatic truth" whatsoever to be accessible. To complete the analogy one must rather imagine something that is both self-interpreting and self-filtering (at this point one also importing "The Library of Babel" into the picture!). Et voila - the UDA! David > On 07 Jun 2014, at 17:23, David Nyman wrote: > > On 12 February 2014 11:17, Bruno Marchal <marc...@ulb.ac.be> wrote: > > At step seven, the primitive materialist can still invoke a physicalist >> form of ultrafinitism, to prevent the comp reversal between physics and >> arithmetic (or number theology). > > > If I've grasped this, it's that one could attempt to avoid the reversal by > claiming that the physical universe isn't (or mightn't be) sufficiently > "robust" (i.e. physically extended?) to instantiate a physical UD that > would run "forever". If so, this would presumably side-step the need to > take the consequent infinities of computations into account. > > > Yees, that the whole point. > > > > > However, I've never felt fully in command of this step, actually. For > example, why couldn't one argue that the physical universe is indeed > sufficiently robust, in the sense intended, to support the infinite running > of a UD, but it simply be the case that - in fact - *there is no such UD in > existence*? > > > > Yes, that certainly exists too. But it is not an interesting protocol to > get the partial reversal of step seven: if there is a concrete UD* then the > laws of physics = "the hunting of the arithmetical rabbits". > > Then in step eight we quasi-eliminate moves like "small universe, or your > robust but without UD, etc." > > > > > > I seem to have missed the force of the implication (at step 7) that a > physically instantiated, infinitely-running UD *must* be taken into > account, given the simple fact of a physical universe sufficiently robust, > *in principle*, to support its existence. > > > At step 7, it is not in principle. Like in the preceding protocol, we just > assume the existence of an infinite running of the UD in our infinite > (then) space-time structure. > > The proposition is that if that is the case, and don't see white rabbits, > it means some computations are multiplied, and exploit (perhaps) the random > oracle inherent in that multiplication. > > > > > IOW, even given the comp assumption, why couldn't one still argue that all > relevant computations - *absent actual physical evidence* of an > infinitely-running UD - in fact supervene on physical brains and/or other > non-biological physical digital machines? > > > By step 8. That moves above is shown introducing a "god-of-the-gap" to > select a reality. It entails a sort of magic distinguishing a computation > from all the others. > > You can do this, as step 8 talk about "reality" and thus can only suggest > the implausibility of such a move. > > It is almost like using an ideology (the belief in a primary physical > universe) to divert from a testable explanation of where the physical laws > come from, and why the physical can hurt. > > It is the same than Omnes, who invoke literally the abandon of rationalism > to select one universe in his otherwise clear description of a (QM) > multiverse. > > The step 8 does not, and cannot, refute your point above, but it can > explain how far it goes near a god-of-the-gap move, or a magic move. It is > close to be proved, as to counteract to step 8 you are forced (in the > transfinite) to provide a matter which is non Turing emulable, and non FPI > recoverable. It looks like reifying a mystery to prevent a possible partial > solution to a mystery. Someone might add that matter needs a "Gods" > blessing, also. > > > Bruno > > > > > > David > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > You received this message because you are subscribed to the Google Groups > "Everything List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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