On 17 May 2017 11:27 a.m., "Bruno Marchal" <marc...@ulb.ac.be> wrote:
On 17 May 2017, at 12:06, David Nyman wrote: On 17 May 2017 8:06 a.m., "Bruno Marchal" <marc...@ulb.ac.be> wrote: On 16 May 2017, at 17:34, David Nyman wrote: On 16 May 2017 at 08:07, Bruno Marchal <marc...@ulb.ac.be> wrote: > > On 15 May 2017, at 22:44, David Nyman wrote: > > > > On 15 May 2017 at 15:56, Bruno Marchal <marc...@ulb.ac.be> wrote: > >> >> On 15 May 2017, at 12:38, David Nyman wrote: >> >> 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 neurological function will be have been replaced by digital componentry 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. >> >> >> OK. For example, you might have accepted a transplant of each individual >> neurons, by pig neuron. But, even here, some implicit computationalism is >> used, in case you agree that the new neurons keep the same finitely >> describable functions. If, not, the very idea of that transplant tends to >> be irrational. You might accept pig's neurons because you believe that pig >> neurons are as much divine than human one, to give an example. >> > > Agreed > > >> >> >> >> >> 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. >> >> >> Careful, because the surgeon might need to explain you why pig's neuron >> can be judged to have the right functional properties, and if such >> explanation is possible in finite time, some mechanist assumption is used. >> > > OK > > >> >> >> >> 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. >> >> >> >> ... or some digital approximation. (to avoid some non-digital mechanism >> hypothesis, à-la Penrose). >> > > OK > > >> >> >> >> 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? >> >> >> It happens that the wave function *is* computable, so this will follow if >> the Hamiltonian itself is computable. Now, it is not too much difficult to >> build (mathematically) a non computable hamiltonian. There is no evidence >> this exists in "nature", but logically, computationalism can be false (and >> in that case, a digital substitution will no more work a priori, or just by >> pure chance, of "just" by the will of some supernatural or non-Turing >> emulable entity). >> >> >> >> >> 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). >> >> >> The problem will be: what do you mean by "physical action"? Human >> perception can depend crucially on physical actions, but physical actions >> might (and have to) emerge from arithmetic. >> > > What I mean by physical action in this context is (approximately) the > conjunction of observed relations between concrete perceptual objects and > an abstract set of "fundamental" transition rules in terms of which these > relations can be both formulated and predicted. > > > I am not sure I understand in this context what you mean by perceptual > object. > Is it brought by a program, or by an infinity of programs? > Is it something computable, or is it recoverable by the first person > indeterminacy? > I mean an object *of* perception (like the apple I see). So it is related to the p of Bp & p. Recoverable by the FPI I guess. Hence what I term above "the relation between concrete perceptual objects" is how correspondence with the facts is primarily established, whether that be a reading on a dial or the abstraction of the intuitive arithmetical notion of 2 from two objects, or from the symbol "2" for that matter. In my view, that is. What happens next is a separate matter. OK. > > > > >> I think that you agree that we are conscious during dreams. In that case >> perception comes from random inputs to the cortex made by the cerebral stem >> (in Hobson theory), and the feeling that we perceive things is build up by >> the brain. few people would say that this is a perception. >> > > I would though. > > > OK? Fair enough, and that answers Brent persistent use of the environment. > > > However, in this case there is no necessary relation with a consistent > covariant externality. > > > I might have lost the line. The question is: is there such a consistent > covariant externality? > I was a little too quick above. What I meant was that in dreaming we are likely to be deluded about any "external reality" we are experiencing because it will tend to be largely an artefact of the perceptual apparatus. That doesn't of course mean that the functioning of that apparatus, or of the organism as a whole, is by that token disconnected from the (more correct) externality associated with the "waking" (or more correct dreaming) state. OK. I would say that a dream is "more correct" when its relative measure is closer to 1. It is more "normal" in the Gaussian sense. The delusion comes to a stop when we realize that there is no "external reality" except for the "arithmetical reality". That would be like the "enlighten state", and/or perhaps death. > The point being made is that we have to justify it from arithmetic. The > "p" in Bp & p is an arithmetical proposition. > Yes of course, assuming comp. To be a little shorter in my remarks, I don't always say this explicitly, but on the basis that comp is being assumed in the argument you can rely on that being my meaning. > > > > Rather, the perception is an artefact of the perceptual apparatus in > semi-isolation from its normal input channels. > > > > This is correct if "normal" means high probability coming from the > infinitely many input channels. Those comes from the infinitely many > universal numbers with oracles competing below our substitution level. > Agreed. Of course that's what normal or typical has to mean in this context. > > > > > > >> >> >> >> >> >> 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) >> >> >> Technically, we need an infinite set of rules or axioms. But that is a >> detail. We can generate UD* wilth a finite set of rules, but each observer >> created in UD*, once Löbian, use infinite set of rules in general (but that >> is a recursive set, so we staty in the mechanist frame). >> >> If you want, []p, or Bp, is all what your brain does when you see an >> apple say. >> > > Yes. > > >> You could translate Bp by "I dream of an apple". Then an observation is >> when the dream fits some reality. Bp & p becomes "I dream of an apple" and >> there is an apple. The relation between both []p and p will be statistical, >> hoping the measure that we get from S4Grz1 (in this case) will work. >> > > Yes again. My use of the expression "procedural commitment to a finite > set of rules" is meant to imply that belief, in this context, is to be > taken to refer to much more than, say, a merely verbal expression. Rather > it implies the commitment of an entire organism to this set of procedures. > > >> >> >> >> and also p (i.e. the "true", or directly incommunicable, correspondence >> between perceptual facts) implied by that belief? >> >> >> Well, implied by the belief, when we restrict ourself to correct machine. >> > > Of course.We are not, in the first instance, dealing with delusions. > > >> The theory explains that this is a not constructive act. We just never >> know if we are awake. We can know that we are dreaming, but we can't know >> that we are awake. >> > > Correct. But we can at least commit ourselves to the belief (i.e. trust, > or as you would have it, bet) that we are dreaming extremely consistently > and pervasively. And if that be so the distinction between that dreaming > and reality becomes otiose. > > > >> Keep in mind that "p" is a proposition of arithmetic. >> > > Ultimately, yes. > > > In some sense. In other sense: we start from arithmetic, and the (sigma_1) > p behave or should behave like physical propositions, when we take the > views (Bp & p, Bp & Dt, Bp & Dt & p) into account. physics is ultimate in > that sense: it needs the statistics on the arithmetical computations. > I think that once one accepts that physics appears as a consequence of the machine-psychological reversal, then physics and computation reach a kind of virtuous explanatory circularity, as Brent often points out. One hand washes the other, as the Russians say. OK. I think this is what can be derived mathematically from the "bisimulation between G and Z (or between G1* and Z1*, ...). But we don't have this with the S4Grz1, or with X1*. One russian hand is bigger and deeper than the other. My image is that the physical is somehow the clothes, or the border of the universal mind (the mind of the "virgin" Löbian machine, or perhaps already the universal machine in general. You are trying to use intuition at the place where I prefer to use the counter-intuitive logic of self-reference. It is OK, as long as we don't get a contradiction with the math. Yes, I may have reached a little too far in the desire to find common ground with Brent. As my most recent comments elsewhere imply, although physics and computation are inextricably entangled in an explanatory embrace as a consequence of the reversal, exactly what each can be taken as explaining is not precisely coequal. Physical explanation is situated within the domain of appearance (alternatively, what is observable or open to interpretation). Consequently it can be taken as explaining net transformations in those appearances. Computational explanation seeks to give an account of how, why and from whose point of view those appearances come to exist, to the extent that such an account can be rendered. To that extent, the abstract or mathematical component of physics is itself computational (insofar as its predicted transformations are finitely computable), but its observable component cannot be so considered without becoming poisoned by intractable ambiguities. Exactly. I might try to add some possible mathematical precision, but I need to think a bit on this. Later. Up to now, the B of Bp & p is interpreted by its computational rendering, but "B" is really provability, and not computation. Up to here, that absence of distinction works well (indeed for a very deep and subtle reason related to Mechanism), but for the precision I want to add, I will need to make the distinction. Are you, and others, OK with those facts: RA cannot prove the consistency of RA. PA cannot prove the consistency of PA, etc. But: PA can prove the consistency of RA. Now the key fact which I intend to use is that RA can prove that PA can prove the consistency of RA. In fact RA can prove also that F can prove the consistency of PA, and of RA. Despite this RA cannot be convinced that those facts prove its own consistency (by incompleteness). Interesting. I think I get your point to the extent that computable is a claim about the formal definability of procedure itself (which IIRC was the goal of Turing's original paper OCN). Provable is by contrast a truth claim: IOW something or other is being shown (i.e. with respect to some point of view) to be the case, i.e. to correspond to some set of (perspectival) facts. So on this account RA itself is not in a position by itself to command such a view of the facts of its own consistency, but it can nevertheless grasp logically that PA is in a position to do so. As a (very) rough and partial analogy, if I am on deck, and you are observing me from aloft, I can grasp that you are in a position to command an entire domain of such personally "unprovable" facts about me, despite my not being in a position to access them. Such personally unprovable facts might also bear directly on questions of my own consistency, for example if I were forced to rely on them in some crucial sense. Say you offered from your superior perspective to "be my eyes" in guiding my survival through some risky predicament below. I might choose to trust that guidance under hazard despite being in no position to prove independently the correctness of such a critical viewpoint. So in such a situation I might be unable to be unambiguously convinced of my own consistency but nonetheless choose to trust in it implicitly in order to promote my survival. Of course this particular intuition pump is more than likely to prove somewhat leaky :( This can be compared with I can emulate Einstein's brain, without being able to understand anything said by Einstein during that emulation. Although crucially I can grasp that, from some perspective, there is an Einstein who is indeed saying something. Of course, were a maximally lazy creator to content itself with devising the UD widget, it could thereby invoke both all possible emulations and their associated understandings without the possibility of anticipating any consequence whatsoever. We, its creatures, by contrast can grasp the consequential existence of points of view within which such understandings can be situated. David This is important to understand that "provable" is very different from computable/simulable. OK? (More on this later) Bruno David > > > >> Even sigma_1 arithmetic. It asserts the existence of state, or of an >> halting computation, or a number. The physical appears only for Bp & p >> (with p sigma_1), or better, with Bp & ~B~p & p. >> > > Yes. > > >> >> >> >> >> 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. >> >> >> That would single out a universal machine, but below our substitution >> level, we need to single it out of the infinitely many universal machine >> which compete to provide your next state. OK? >> > > Yes. IIUC, this would be determined by the predominance of (relatively) > highly stable, > > > Yes, but not just the predominance. the logical structure imposed by the > views might play a role in weighing the computations as seen by a subject. > Yes of course. In fact IMO the relevant predominance is that of the narrative consistency, pervasiveness and stability imposed *by that very logical structure*. So what would have to predominate, for this view to be plausible, is the net monopsychic effect of a relatively pervasive remembering (literally "putting together") of those compelling and consistent personal narratives. This may be conceived as the "positive" pole of a sort of subjective ambiguity, whose "negative" antipole is an at least equally pervasive forgetfulness and cancelling out of consequence, to the effective relative exclusion of the myriad competing subjectively pathological fragments. My rough analogy in this case, you may recall, was akin to having your attention totally riveted by a very compelling and coherent speaker standing very close to you. The thought then is that the competing babble of random fragments emanating from a noisy surrounding environment cannot compete, with any lasting consequence, relative to that repertoire of powerful and consistently connected narratives. > > > > pervasive and consistent relations between arbitrarily many machine > points of view. It is these characteristics that in effect would extract > the necessary first-person plural measure, if this view of the matter is > ultimately to succeed. As discussed before, it would be necessary for > pathological segments of narrative (aka white rabbits) to mutually cancel > or be swamped (from the first-person perspective) in the monopsychic > measure struggle between forgetting and remembering. I don't know if the > various intuitive analogies I've sketched recently are any help in thinking > about this. I rather liked the one about the compelling orator and the > background of babble. > > >> >> >> >> >> >> 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? >> >> >> Well, usually we start from computationalism (basically because we have >> no other theory except for fairy tales). The conjunction in Bp & p is added >> (by Theaetetus) because Socrates, like Gödel for provability, destroys the >> link between Bp and p. Most people would say that when we prove things >> (=when we justify things rationally), it ought to be true. But Socrates >> said that some people can be wrong in their reasoning, or can have false >> premise, or that we could dream, etc.), and Gödel shows that no correct >> machine can prove its own Bp -> p, nor its own Bp <-> (Bp & p). We need >> faith all the time, in "real life", but we can reason on simpler (but still >> Löbian) than us machine, and lift, privately, the theology of that machine >> on us. But that is at our risk and peril, all the times, and it becomes >> explicit with the "yes doctor". >> > > Yes, but I think there are important nuances with respect to "true" that > have frequently been missed in these conversations. The first nuance is > that there is a primary truth entailed by Bp which is simply the perceptual > "facts" it implies. > > > Bp -> p is true in the eye of God, but the machine cannot know that. > The machine cannot know that but the person implied by the machine knows its primary truth beyond doubt. OK. That is normally captured by the fact that for each p that the machine can actually prove, Bp -> p will be provable "trivially" (in classical and intuitionist logic, of you can prove p, you can prove (<anything> -> p). Note that for a machine which is unsound Bp & p can be actually false, in fact p can be false. It is madness: case where we know something false. That does not exist in my setting, because I limit myself to correct machine. What can however be doubted is what exactly it refers to and what action to take as a consequence. > Somehow p comes "first" (in a logical sense), > Yes, that's implied in a sense by what I said above. > then comes Bp, which is a bit like a window on reality. > It's also the actionable component of Bp & p. Yes. > It is "p" as seen/believed by the subject, who can publicly share "Bp", > Believed rather than seen, perhaps. IOW the action taken, as remarked above. Yes. In fact "seen" is ambiguous, but make sense in case the physical measure exists. To see is just to believe/dream relatively to a normal sheaf of computations. > but only hope for p, or hope in his own correctness. > Yes, it can hope that the direct perception of p (or IOW the semantics implied by the syntax of Bp) won't lead it into mistaken belief or action. > > > > This, if you like, is simply the fact of the dream itself, without any > necessary entailment to a consistently covarying externality. This, as > mentioned above, can be considered an ineliminable artefact of the > perceptual apparatus. It is only after this primary fact (i.e. the second > nuance) that considerations of consistent reference to such an externality > can be considered, and it is at this point that we can fall into error and > be deluded. As you say above, we can never be absolutely sure what our > dreams refer to, since the perceptual apparatus must be substantially the > same in all cases. Hence we can only believe and act in good faith. > > >> Don't hesitate to tell me if I missed your question. It might help to >> keep in mind that there is no physical reality: only dreams. >> > > I think we agree. > > > I think too. We could differ only the intuition pump though, perhaps. No > problem, we need a lot of such pump, perhaps a different one for each > individuals. > All hands to the pumps ;) :) Bruno David > > Bruno > > > > >> Knowing is when the dream are arithmetically true, and physical >> observation is when the dream is arithmetically probable. Immediate feeling >> is when the dream is probable and true. >> > > Yup. > > David > >> >> 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 https://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 https://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. > 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. > > > 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 https://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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