On 8 May 2017 7:26 a.m., "Bruce Kellett" <[email protected]> wrote:
On 8/05/2017 3:59 pm, David Nyman wrote: On 8 May 2017 4:53 a.m., "Bruce Kellett" < <[email protected]> [email protected]> wrote: On 8/05/2017 3:14 am, David Nyman wrote: On 6 May 2017 11:04 p.m., "Brent Meeker" < <[email protected]> [email protected]> wrote: On 5/6/2017 2:45 PM, David Nyman wrote: On 6 May 2017 10:16 p.m., "Brent Meeker" < <[email protected]> [email protected]> wrote: But that's what I mean when I say Bruno's theory has no predictive success. QM (and Everett) would correctly predict that alcohol molecules in the blood will interfere with neuronal function and THEN invoking the physicalist theory of mind, i.e. that mind supervenes on material events, it predicts that your ability to do arithmetic will be impaired by drinking tequila. It will NOT predict the contrary with more than infinitesimal probability. So it's misdirection to say that it's just a measure problem. Without having the right measure a probabilistic theory is just fantasy...or magic as Bruno would say. I have no idea why you say that. I thought it was clear that if computationalism doesn't (ultimately) predict that its predominating computational mechanism (i.e. the one effectively self-selected by complex subjects, in this case, like ourselves) is the physics those selfsame subjects observe, That would certainly be an accomplishment - which in another post Bruno says is trivially accomplished even in RA (I don't see it). But to succeed in prediction it is not enough to show that some world exists in which mind and physics are consistent (that the physics that mind infers is also the real physics that predicts effects on the mind). You need also to show this has large measure relative to contrary worlds. One can make a logic chopping argument that it must be that way for otherwise minds would not be making sense of the physics they perceived - but that makes the whole computational argument otiose. I've been thinking a bit more about this and I'd like to set out some further tentative remarks about the above. Your professional expertise in these matters is orders of magnitude greater than mine and consequently any comments you might make would be very helpful. By the way, it would also be helpful if you would read beyond the next paragraph before commenting because I hope I will come by myself to the fly in the ointment. Firstly, and "assuming computationalism" on the basis of CT + YD, we are led to the view that UD* must include all possible "physical" computational continuations (actually infinitely reiterated). This of course is also to assume that all such continuations are finitely computable (i.e. halting). Now, again on the same assumptions, it might seem reasonable that our observing such a physics in concrete substantial form is evidence of its emergence (i.e. epistemologically) as the predominant computational mechanism underlying those very perceptions. Hence it might seem equally reasonable to conclude that this is the reason that these latter correspondingly appear to supervene on concrete physical manifestations in their effective environment. Now wait a minute. We cannot escape the question of measure. Why would it be reasonable to assume that a physics of this sort should predominate in the manner outlined above? Well, firstly, it would seem that the generator of the set of possible physical computations is infinitely reiterative and hence very robust (both in the sense of computational inclusiveness a la step 7, and that of internal self-consistency). But who is to say that the generators of "magical" or simply inconsistent continuations aren't equally or even more prevalent? After all we're dealing with a Library of Babel here and the Vast majority of any such library is bound to be gibberish. Well, I'm wondering about an analogy with Feynman's path integral idea (comments particularly appreciated here). Might a kind of least action principle be applicable here, such that internally consistent computations self-reinforce, whereas inconsistent ones in effect self-cancel? Also, absence of evidence isn't evidence of absence. I'm thinking here about the evaluation of what we typically remember having experienced. I can't help invoking Hoyle here again (sorry). Subjectively speaking, there's a kind of struggle always in process between remembering and forgetting. So on the basis suggested above, and from the abstract point of view of Hoyle's singular agent (or equally Bruno's virgin machine), inconsistent paths might plausibly tend to result, in effect, in a net (unintelligible) forgetting and contrariwise, self-consistent paths might equally plausibly result in a net (intelligible) remembering. I'm speaking of consistent and hence intelligible "personal histories" here. But perhaps you would substitute "implausibly" above. Anyway, your comments as ever particularly appreciated. I think the problem here is the use of the word "consistent". You refer to "internally consistent computations" and "consistent and hence intelligible 'personal histories'." But what is the measure of such consistency? You cannot use the idea of 'consistent according to some physical laws', because it is those laws that you are supposedly deriving -- they cannot form part of the derivation. I don't think any notion of logical consistency can fill the bill here. It is logically consistent that my present conscious moment, with its rich record of memories of a physical world, stretching back to childhood, is all an illusion of the momentary point in a computational history: the continuation of this computation back into the past, and forward into the future, could be just white noise! That is not logically inconsistent, or comutationally inconsistent. It is inconsistent only with the physical laws of conservation and persistence. But at this point, you do not have such laws! In fact, just as Boltzmann realized in the Boltzmann brain problem, states of complete randomness both before and after our current conscious moment are overwhelmingly more likley than that our present moment is immersed in a physics that involves exceptionless conservation laws, so that the past and future can both be evolved from our present state by the application of persistent and pervasive physical laws. Unless you can give some meaning to the concept of "consistent" that does not just beg the question, then I think Boltzmann's problem will destroy your search for some 'measure' that makes our experience of physical laws (any physical laws, not just those we actually observe) overwhelmingly likely. Thanks for this. However I'm not sure you've fully addressed my "path integral" point, for what it's worth. Feynman's idea, if I've got the gist of it, was that an electron could be considered as taking every possible path from A to B, but that the direct or short paths could be considered as mutually reinforcing and the indirect or longer paths as mutually cancelling. Feynman's ideas relies on a physical theory within which one can calculate the phase change along each possible path. The upshot is that paths far away from the path of least action have phases that cancel in the quantum superposition sense. Note that the crucial input into this picture is that there is an underlying physical theory, in terms of which one can calculate the phase changes along each path. Also, it is important to remember that Feynman's path integral is only one means of calculating probability amplitudes in QM -- there are many other means of calculating these, and all give the same results. Sure, it was only meant to be illustrative, but I still think the in-phase/out of phase analogy may have some intuitive merit. Hence the derivation of the principle of least action. So the analogy, more or less, that I have in mind is that Boltzmann-type random subjective states would, computationally speaking, mutually reinforce identical states supervening on the generator of "consistent" physical continuations (bear with me for a moment on the applicable sense of "consistent" here). IOW "If I am a machine I cannot know which machine I am". So as long as the generator of those consistent states is encapsulated by UD* - which is equivalent to saying as long as the computable evolution of physical states is so encapsulated (which it is by assumption) - then we can plausibly suppose that the net subjective consequences would be indistinguishable. I agree that conscious states, whether Boltzmann brains or parts of a longer calculation that does not start and end in white noise, are, insofar as thise states are conscious, they are indistinguishable. But the Boltzmann brain-type states cannot reinforce the path that leads to coherent physics, because the continuations are disjoint. Doesn't matter as long as they don't interfere, surely. As to your most reasonable request for a non question begging notion of consistent in this context, my tentative answer rests on my remarks about the "struggle between remembering and forgetting". Here's where I use Hoyle's pigeon hole analogy, which is pretty much equivalent to Barbour's time capsule one (as he acknowledges in TEOT) Both Hoyle's pigeon holes and Barbour's time capsules assume that there is a coherent underlying physics with regular exceptionless laws. Until you have something like that, you cannot define consistent continuations. But I'm afraid that's implied by assumption unless one takes the view that the evolution of physical states is fundamentally incomputable, in which case, computationally speaking, all bets are off. On this assumption UD* must encapsulate the generator of, in effect, pervasive, persistent and exceptionless laws. This isn't precisely a derivation of physics, I readily concede, but perhaps this is too much to demand of what is at this stage a toy model. One only has to show that the measure of this physics can overcome interference from the infinities of Babelish gibberish. or for that matter the "point of view" of a machine computing a partitioned multitasking OS. All of these analogies, or heuristics as I prefer to think of them, enable one to think about the entirety of subjective experience as though from the first person perspective of a single agent - one of course with a massive case of multiple personality accompanied by extreme dissociation between each of the personalities. The only connectivity between discrete states of the overall system is that which is logically internal to each state. But what gives that internal logic? Boltzmann brains are internally logical in their own terms. If you take your present memories of a past world as part of your conscious state, and require that future continuations be consistent with those memories (along Barbour's time capsule lines), then you are building most of physics into your notion of consciousness. This may very well be what is required, but I do not see that as an explanation of consciouness in terms of arithmetical realism or computationalism, or as an explanation of physics in terms of the UD. Of course on reflection we realise that most plausibly the brain must somehow contrive just such relations between states, as becomes most obvious when this mechanism goes wrong in dementia and other neurocognitive insults. But you know this only from your experience of the physical world -- that is not currently in evidence. I'm just saying it's consistent with experience. So "consistency" here would reflect the fact that these very conversations, for example, form part of a coherent internally linked history of remembering, whereas inummerable incoherent states simply *cannot be recalled* from the perspective of such consistent histories. Hence what is consistent is equivalent to what is, in the net, remembered (recalling in passing the etymology of this word) as distinct from what is, in the net, disremembered. But how do you know that your memories are veridicial of anything at all -- they could just be fluctuated into existence as part of your momentary conscious state. But my point is that mutual reinforcement makes this irrelevant given the presence of a consistent physics by assumption. We only need to eliminate the interference factor. I'm reasonably confident that this justification isn't merely circular, or that if it is, it may well be one of Brent's virtuously circular explanations. What do you think? I don't think the circle is virtuous. You are required to define "consistent" in a way that does not refer to physical laws. I don't agree. We only need to show how interference from inconsistencies can be eliminated, thus allowing the consistent physical measure to predominate as the computational mechanism underlying perception. David The only other consistency that I know is logical consistency, and mere logical consistency does not avoid the Boltzmann brain problem. Bruce -- 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 [email protected]. To post to this group, send email to [email protected]. 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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