I've been thinking a bit about physical supervenience in the computationalist context and have come to the conclusion that I don't really understand it. So let's consider CT + YD. YD means accepting the replacement of all or part of my brain with a digital prosthesis. Now, whatever theory the doctor may vouchsafe me with respect to the function of this device, the replacement will FAPP be, in the first (and last) instance, a physical one. IOW after the procedure some are all of my neurological function will be have been replaced by digital componentry (presumably some species of logic gates) that putatively (sufficiently) faithfully mirrors the function of the biology that has been replaced. From any extrinsic perspective, all that will have happened (assuming the success of the procedure) is that the net physical behaviour of my generic brain will have been preserved to the required extent. Notice that there is no necessary reference to computation per se so far, however much we may wish to appeal to it in explicating what is "actually" supposed to have occurred. In a minimal sense supervenience will have been satisfied, in that my behaviour will continue to covary systematically with the net physical action of my generic brain, but there is no necessary reference to computation in this. And indeed if the proposition of CTM were simply based on YD alone, there would seem to be no further criteria to satisfy. However, with the additional assumption of CT, it would still seem necessary to make a further step towards explicating the relation between the above mentioned net physical action and the relevant spectrum of computation deemed to underlie both it and the (perceptually) substantial terms in which it is subjectively made manifest. The use of the word "net" in the above is noteworthy as a little reflection will remind us that, no matter how many "layers" of software are in principle being implemented on a given hardware, the only relevant observable consequence is their net physical effect, which may be rendered entirely minimal, or even be approximated adventitiously.
It has been asserted that "physics" emerges epistemologically as a consequence of the net perceptual integration (aka the psychology) of an infinity of digital machines. We can say this because of the formal equivalence of the class of such machines. This in effect equates, in a certain relevant sense, to their having a single such psychology, or monopsychism, albeit one that must be highly compartmentalised by programming and the contents of memory. In this sense, it may be possible to analogise this monopsychic perceptual position as akin to that of a multitasking OS running on a single "processor". There are at least two aspects to the physics of which we speak. The most obvious aspect is the observed behaviour of any physical system under study, which must always be rendered in terms of the net change in some set of concrete perceptual markers (e.g. the classic needle and dial). The second aspect is however unobservable in principle and consists of an abstract set of transition rules between physical states (assumed to be finitely computable, according to CTM) between observations. For present purposes, we may perhaps consider these rules to be represented by the wave equation which describes the unitary evolution of physical states. A question now occurs to me. On the foregoing presuppositions, are we to suppose that the computations representing the abstract unitary transition "rules" of the wavefunction (i.e. the second, abstract, part above) are *the selfsame ones* that, (under an alternative but putatively compatible logical interpretation) are supposed also to explicate the concrete perceptions in terms of which the observations (i.e. the first, perceptual, part) are made? If this were the case, we could indeed say that perception supervened both on computation (under one interpretation) and observed physical action (under a different but compatible one). Is this compatibility in effect what is meant by Bp (i.e. the communicable "belief in", or procedural commitment to, a finite set of rules) and also p (i.e. the "true", or directly incommunicable, correspondence between perceptual facts) implied by that belief? If this were indeed the case, then the indispensable characteristic of the necessary physics (i.e. the second, abstract, part) that would permit it to be singled out perceptually from the dross of the computational Babel in this way would it be sufficiently "robust" in the relevant sense. That robustness would consist firstly in the capacity to stabilise the emulation of an (ultimately monopsychic) class of perceptual machines. And secondly in that the necessary machine psychology would supervene on common computational transition rules resulting in a (sufficiently) consistent covariance with a concrete externality as perceived by those selfsame machines. The conjunction of those rules and that observed externality would then be what we call physics and the computational physics so particularised would in effect be distinguished by its intrinsic capacity for self-interpretation and self-observation. Does this make sense and if it does, what in particular about the computationalist assumptions or inferences make such a very specific conjunction plausible? 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 https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
