On 02 Sep 2009, at 03:17, Brent Meeker wrote:

> But only by isolating a bit of computation from the rest of universe. > And it doesn't show that a computation supervenes on zero physical > activity. And even if it did show that, it would not follow that > mental > computation *does* supervene on computation realized in Platonia with > zero physical activity. Maudlin's Olympia shows that a computation can be realized with zero *computational* physical activity, and this means that if we keep associating the consciousness to the computation, the physical activity has no role there. MGA shows that if we associate consciousness to the physical activity implementing a computation, then we have to associate that consciousness "in real time" to a description of that computation, which can be seen as absurd in different ways. We can come back on this, but I think it is better I explain what mathematician means by computations. MGA and MGA-like argument can be seen as an extension of what is done in UDA1-6. It shows that a universal machine cannot see the difference between "real", "virtual" and then "arithmetical". But like the notion of virtual emulation has to be grasped for the step 6, the notion of arithmetical computation has to be grasped before, and that is why I am explaining the mathematician definition of universal machine and its computations. > > >> This is an absurd conclusion, so the hypothesis that motivates it - >> i.e. CTM+PM - is thus shown to be contradictory and must be >> abandoned, >> not merely in this case, but in general: i.e. the exception has >> broken >> the rule. This is forced unless you can show where the logic goes >> wrong. >> > No, even if the conclusion is wrong that only shows that *some* step > in > the argument is wrong NOT that the conjunction of the computationalist > theory of mind and primary matter is self contradictory. You can say this for any proof by reduction ad absurdo. But if someone pretend having done a reduction of absurdo of A+B, that is, pretend to have provide a proof, or argument, that A+B -> false, then if you disagree that this leads to ~(A+B), you have to *find* at which step the error is. That's the very idea of proving. Of course in a difficult "applied" subject, you can always find some loophole of the kind "invisible horses driving cars", and it is a matter of pedagogy to explains things spirit, instead of big set of formalities capable of satisfying everyone in the first strike. In the present case, you can always develop a sufficiently ridiculous notion of matter and physical computation to block the proof, but it should be clear that a strong change of the meaning of the hypothesis is done. > I don't even > see where the argument uses PM to reach its conclusion. Note that "PM" is used in all UDA1-7, and at that stage, you can still argue that the supposedly existing physical universe is too little to run a big part of the UD, (but we have already the result that comp entails indeterminacy and non-locality). The step 8 just shows that the move toward a "little physical universe" does not really work, in the sense that the physical supervenience thesis, in the comp frame, entails that we can show the physical activity non relevant with respect to the computation. You have to believe that consciousness "in real time" is related to static description of such computation, which is perhaps not contradictory, but is non sensical. You can no more say yes to the doctor 'qua computatio'. > Maybe CTM+UD is > a simpler explanation of the world, a return to Platonic idealism, > but I > don't see that its contrary is contrdictory. It is contradictory with the idea that consciousness is related to both the computation and the physical activity, in the PM sense of physical activity. A movie of a brain become conscious qua computation and without computation. It is not a mathematical contradiction, but a conceptual difficulty preventing saying "yes to the doctor" by appealing to the notion of computation. Like invisible horses pulling cars could throw doubt to the thermodynamical explanation of car motor. As I have always said, MGA does not eliminate completely some use of Occam; it minimizes it, but, like always in applied math, you can imagine a sufficiently bizarre notion of physical computation to stuck the logic of the applied proof, a bit like your own move of associating your consciousness to a non computable physical object outside your brain. But with the generalized brain, this is taking into account. If your consciousness, to exist, needs that uncomputable object, you are no more in the comp frame. It is like the collapse of the wave packet. It shows that the many- worlds does not follow logically from the SWE, and the collapse is so badly defined, that you can hardy evacuate it (like the God-of-the-gap in physics), yet, I do think that the many-words follows directly from the SWE, because the collapse is just that, an ad hoc construction, undefinable in the theory, introduced to keep the consequence under the rug. Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---