On Sun, Sep 28, 2014 at 06:46:24PM +0200, Bruno Marchal wrote: > > > >Additionally, in a robust universe, the Church-Turing thesis tells us > >that physics we supervene on must be emergent from the properties of > >universal systems (Bruno's reversal result). Thus the matter we > >supervene > >on cannot be "primitive". The primitive urstuff is something else > >entirely - the arithmetic of integers, perhaps, as Bruno suggests - > >but not matter as we know it. > > I would say that there is no primitive urstuff at all, nor any > physical universe, robust or not. >
I introduced the term "urstuff" as a way of referring to what is ontologically real. "primitive urstuff" is a tautology, of course, as urstuff is primitive by definition. Urstuff could be matter, or it could be a platonic system like the integers. Since we can never know what it is, we should Wittgensteinly shut our traps about it, but since we don't seem to be able to do that, we need a label to talk about it. > >> > > > >It demonstrates an inconsistency between physical supervenience and > >computational supervenience, notably that physical supervenience > >entails that certain very simple computations, such as the replaying > >of a recording, will be conscious. > > > >This only works in a non-robust universe, however, a point that is > >often overlooked in treatments of this. > > > It seems to me that the MGA makes the robust/non-robustness > irrelevant. It is enough that elementary arithmetic, or the > combinators, is a robust reality. > I agree. The whole non-robust universe move is a rejection of your AR postulate. But it does seem reasonable to ask what might happen if not all possible programs could exist, ie that the Turing model of computation is constrained in some way. I guess essential if you really want to tackle Aristotelianism in its home ground. > The ultrafinitist physicalism has still to endow his "existing > matter" with magical non-Turing emulable to make its reality doing > the selection it seems to me. > I agree it is non-Turing, but magical might be a bit too strong an epithet. The argument, presumably, is that some computations require too great a resource in order to be instantiated. (By analogy with Norm Wildberger's main argument against infinity). -- ---------------------------------------------------------------------------- Prof Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Professor of Mathematics hpco...@hpcoders.com.au University of New South Wales http://www.hpcoders.com.au Latest project: The Amoeba's Secret (http://www.hpcoders.com.au/AmoebasSecret.html) ---------------------------------------------------------------------------- -- 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.
