On Thu, Oct 15, 2015 at 7:36 PM, Bruce Kellett <[email protected]> wrote:
> On 16/10/2015 9:46 am, Jason Resch wrote: > > On Thu, Oct 15, 2015 at 5:26 PM, Bruce Kellett <[email protected]> > wrote: > >> On 16/10/2015 8:56 am, Jason Resch wrote: >> >> On Thu, Oct 15, 2015 at 12:34 AM, Bruce Kellett < >> <[email protected]>[email protected]> wrote: >> >>> >>> What evidence do you need to say that something does not exist? Absence >>> of evidence is, in this case, evidence of absence. >>> >> >> Why is that so in this case, when the standard form of that phrase is >> "Absence of evidence is not evidence of absence"? >> >> >> Because if there is no evidence for something where one would, if that >> thing existed, expect evidence, then one is justified in saying that the >> thing does not exist. >> > > So what evidence would you expect to see if platonic computations existed? > > > Evidence of conscious beings independent of any physical substrate. In > other words, ghosts and the other insubstantial beings of popular mythology > and fiction. I see no evidence of such beings where might expect to see it > if they existed, so I conclude that they do not exist. > For your eyes to see them, they would need to be capable of manifesting physical effects in this universe. E.g. they would have to be physical and part of this universe. But we defined them as separate from and independent of this universe. Therefore, we should not expect to see them with our eyes or any other physical measurement apparatus. This reminds me of the letter Everett wrote to Dewitt to convince him that his inability to feel himself splitting could not count as evidence that he was not splitting, for the theory explained why he would not be able to feel himself split: http://www.pbs.org/wgbh/nova/manyworlds/orig-02.html A crucial point in deciding on a theory is that one does *not *accept or reject the theory on the basis of whether the basic world picture it presents is compatible with everyday experience. Rather, one accepts or rejects on the basis of whether or not the *experience which is predicted by the theory* is in accord with actual experience. Let me clarify this point. One of the basic criticisms leveled against the Copernican theory was that "the mobility of the earth as a real physical fact is incompatible with the common sense interpretation of nature." In other words, as any fool can plainly see the earth doesn't *really* move because we don't experience any motion. However, a theory which involves the motion of the earth is not difficult to swallow if it is a complete enough theory that one can also deduce that no motion will be felt by the earth's inhabitants (as was possible with Newtonian physics). Thus, in order to decide whether or not a theory contradicts our experience, it is necessary to see what the theory itself predicts our experience will be. Now in your letter you say, "the trajectory of the memory configuration of a real physical observer, on the other hand, does *not* branch. I can testify to this from personal introspection, as can you. I simply do *not* branch." I can't resist asking: Do you feel the motion of the earth? > > > > If there were an elephant in my room at this moment, I would expect to see >> it when I turned round. The fact that I do not see an elephant when I turn >> round is good evidence that there is no elephant in my room. Absence of >> evidence is evidence of absence. >> > > Bruno has shown that one thing we would expect to see is a quantum > reality. And what do we see? > > > Bruno has shown no such thing. > Have you fully read and fully understood Bruno's work on this? > > > Also, despite your claims to there being no evidence, there is in fact > evidence of platonic computations. They exist independently of you, mean, > and this physical universe, as surely as "7 is prime" is true independently > of you, me and the physical universe. > > > The statement "7 is prime" is true by virtue of the axioms of arithmetic > and the definition of a prime number. That does not imply that "7" exists > in any sense whatsoever. > > It does if you accept the truth of the axioms. Do you deny the axioms are > true? > > > As a general matter, yes. Axioms are not true or false, per se. They can > only ever be 'true' in particulr models. They are 'true' in some, and not > in others. I refer you to my concurrent discussion with Bruno. > But in any model of the integers, 7 is prime will be true, and "7 exists" is a provably true statement. > > > You confuse "true" being used of a proposition, with "exists". That is a >> profound and serious confusion. >> > > The truth of "7 is prime" implies no integer factors of 7 exist besides 1 > and 7. The truth of "8 is composite" implies the existence of integer > factors of 8 besides 1 and 8. I do not confuse truth with existence. It is > the truth of a proof of existence that implies existence. > > Perhaps of existence within that formal system. But you must be careful to > distinguish between the notions of 'exist' as meaning that there is a true > proposition in some formal system about that object, and 'exist' as in > physical existence -- there is a physical object corresponding to that > description. > Certainly. > So "7" exists in the sense that there is a true proposition in formal > arithmetic which states that "7" is prime. But there is no physical object > corresponding to that abstract notion of "7". > I agree, 7 is not physical. Nor are the functions that compute pi, or the evolution of the wavefunction for the state of the milkyway galaxy. But the existence of the latter will result in conscious beings who believe in a physical world. > Confusing the two meanings of the word 'exist' lies at the heart of all > your reasoning. And that is why I am so easily able to dismiss it. > > All I find in your dismissals is a blind willingness to believe in what you see, and an equally blind willingness to deny that which you do not see. Unlike you, I cannot so easily dismiss those things that I cannot see, and have good reason to believe I would not be able to see even if they existed. > > In mathematics you have descriptions of Turing machines and descriptions >>> of computations, but no live machines or computations. >>> >> >> There are both. >> >> >> What evidence do you have for this assertion? >> > > The existence of a UD implies a quantum reality, and we observe a quantum > reality. > Accepting the truth of arithmetical systems like the axioms of > Peano/Robinson arithmetic, implies their existence. > > > But I do not accept the 'truth' of these mathematical structures. > > How can you do physics if you cannot count or add one number to another? > > > I can count without believing that numbers exist independently of their > physical representation. > You cannot justify the correctness of your counting without an implicit belief in the correctness of the axioms that define addition. And those axioms say nothing about the requirement of a physical representation to be valid. > > > > And, even if taken as a set of axioms upon which one can reason, they do >> not imply that anything like a UD actually exists in any useful sense. The >> UD is an idea in platonia, and it is totally without function until it >> receives a physical implementation. >> > > So then the Bruce Kellet that exist within a platonic calculation of a > simulation of the milky way galaxy on the Planck scale is a zombie? Too bad > for him, that his galaxy is only "abstract", rather than "concrete". > > > Ah, but there you betray the essential importance of the physical > substrate. You are simulating a galaxy to support a conscious being. And > that simulation is, of necessity, carried out on a physical computer. You > have not yet given evidence of any consciousness existing without such a > physical substrate. > I have in a post to John Clarke. If you can ever get to a point where you believe "7 is prime" is a truth independent of you or the world, then it is not much of a leap to get to the belief that "P(P(P( ... (x) ... ))) = y" is true independently of you or the world. Now when P is a function that computes one step of a Turing machine, and X is number representing a program that implements a conscious mind, then you can say this computation exists as a consequence of platonic truth concerning statements in arithmetic. You can prove that such an iterated P exists, and also prove each step of the computation resulting in the corresponding changes to the tape. You can also prove that the "simulated brain" of this conscious mind, updates itself in response to its experienced environment or other inputs it might receive over the course of its execution. > > > Substrate independence simply means that you can replace all or part of >> the human brain with computer-based equivalents. In other words, strong AI. >> No need for platonia in order to say that consciousness is independent of >> the substrate. >> > > But if it is independent of substrate, and if computations exist > platonically, then those platonic computations are equally capable of > instantiating consciousness. > > > You are confusing the meaning of 'substrate'. In the context, I meant an > explicitly physical substrate. Platonia is an idea, > > If Platonia is an idea, then so is "The primary physical reality". It is > up to science now, to determine which of these two ideas is more likely to > be true. > > > Sure. And science has proved many times over that physical reality exists > and can be operated on, while platonia is an idea that has no useful > consequences whatsoever. > > Science has never proven that the physical reality is not merely an > appearance to conscious entities that exist as a consequence of > platonically existing computations. > > > No, but any credibility that that hypothesis might have depends on there > being independent evidence for the possibility of platonically existing > computations. And there is no such evidence. > There is but when I tell you this, you put your head in the sand and deny it. > > > it is no more 'physically real' than is the idea of a unicorn, or of >> Hogwarts School. >> > > Of course it isn't physically real. But why assume physical existence is > the only kind of existence? That seems to be an idea based purely faith. > > > Can I take your lack of reply to mean you agree that it is only by pure > faith that you believe physical existence is the only kind of existence? > > > I did not reply earlier because no reply to such a comment seemed > necessary. I do not say that physical existence is the only way in which > the word 'exist' is ever used. It is used in the sense of the mathematical > existential quantifier, and it is often used of ideas, and other > non-material things, in a metaphorical sense. It is the failure to clearly > distinguish between these different senses of the word 'exists' that cause > most of your confusion. > So turing machines that exist in mathematics cannot produce consciousness. But turing machines that exist in mathematics can produce consciousness. Forgive me but I don't understand how you arrived at this conclusion. > > > Neither unicorns nor Hogwarts can instantiate consciousness. No more can >>> the idea of platonia. >>> >> >> The idea of platonia doesn't instantiate consciousness, but objects >> within platonia do. >> >> >> Prove it by showing me this magical platonic conscious being. >> > > Look in the nearest mirror. > > > I know that when I look in the mirror, I cannot see the actual goo > constituting my brain, but that does not mean that I do not believe in its > existence. The object I see in the mirror is the exterior of a conscious > physical being -- the operational word being 'physical'. Not a platonic > idea. > It's the experience of a conscious being looking in a mirror. Which by computationalism, one cannot distinguish from a computation within arithmetic, a computation without a physical world, or a computation within a simulation run in some alien's world. > > > >> If you want to demonstrate that the idea of platonia can sustain >> consciousness of itself, then all you have to do is produce a conscious >> being that does not have an accompanying physical substrate. Until you do >> that, I think you should shut up about platonia. >> > > Would you demand of Everett to produce a conscious being from another > branch of the wave function, or else shut up about the other branches of > the wave function? > > > Yes, of course. The other branches of the wave function are not real in > any useful sense. They are an idea, just as is platonia. And ideas can have > effects in the real world only through the intermediary action of conscious > physical beings, never by magic. > > They are consequences of testable theories, mainly QM. You believe in the > existence of galaxies so far away we may never see them, don't you? > > > Because of the expansion of the universe, galaxies that we once could see > are passing over the Hubble horizon all the time, such that we can no > longer communicate with them. But there is still good indirect evidence of > their existence. > So you're saying you believe in the existence of galaxies we will never see because they are consequences of our theories (namely inflation). > But I have no such evidence for the existence of Everettian many-worlds. > They are not necessary consequences of QM. > They are consequences of taking the equations of QM literally, rather than relegating them to some "calculating tool" instead of a description of reality. If you take the equations of QM as literally as you take the theory of inflation, I think you would accept the many worlds as a consequence of the theory. Why do you think inflation describes the universe rather than being a mere "calculating tool" to calculate how smooth space would be if it really did inflate (but in fact it does not because inflation is just a "calculating tool"). > You seem unaware of the fact that QM can be developed and used, with > complete adequacy, without ever introducing the idea of a wave function, or > of the Schrodinger equation. Both Dirac and Schwinger have developed such > theories. So if the wave function is not a necessary part of quantum > mechanics, then it would be unwise to put too much faith in the > consequences of reifying this abstract calculational tool. > > I guess it would be equally unwise to put too much faith in the universe being substantially larger that the small sphere within which light has had enough time to reach our eyes. > Also, talking of purely theoretical evidence for things, like inflation > and so on, why would cosmologists put so much effort into finding > confirmatory direct evidence for the 'other worlds' predicted by inflation > if everything predicted by a widely accepted theory could be taken as > 'true'? In science, anything that is lacking independent confirmatory > evidence must always be regarded as hypothetical, or provisional. > That's what science is. Trying to overthrow prevailing theories by finding evidence that would disprove them. It is through this process that confidence can build in the theories that have survived such an effort. Speaking of that, I am aware of no successes in Peano Arithmetic being disproven or shown to be inconsistent. > > > If not, then why demand that I shut up about the consequences of > well-accepted theories? > > > Well-accepted? > > > Laws of arithmetic. Computationalism. > > > Why? Arithmetic is system of propositions. Whether it is real or not has >> no effect on Church-Turing. >> > > Then you should be equally happy to have your brain implemented by "unreal > computations" as "real computations" :-) > > > Computations in platonia are 'unreal' -- they do not exist, so cannot > implement anything. > > > You said earlier that you have no evidence that objects of platonia do not > exist. So why insist so adamantly that they do not? > > > You should learn to read. I said no such thing. I said that the absence of > evidence for platonia was evidence that it did not exist. > > Strange how evidence works. No evidence = evidence? > > > Yes, funny that. Get used to it! > > Are you familiar with Max Tegmark's idea that physical existence is > mathematical existence? > > - https://en.wikipedia.org/wiki/Mathematical_universe_hypothesis > - http://arxiv.org/pdf/0704.0646.pdf > - > > http://www.amazon.com/Our-Mathematical-Universe-Ultimate-Reality/dp/0307599809 > > > I am familiar with Tegmark's ideas. I do not agree with most of them. > Arguments from authority do not carry weight here. Tegmark is an outsider > in the physics community. > > I was not making an argument from authority, only pointing you to some > material that might cast doubt on your belief that physical existence is > somehow different from mathematical existence. Also, "Tegmark is an > outsider in the physics community" is an argument from authority (the > authority of the physicists that have ostracized him). > > > Tegmark's ideas lack independent evidential confirmation, so they are not > widely accepted. This is an argument from the authority of evidence, if you > like, not just from the authority of the scientific community. > > Since you are familiar with his ideas, I ask you, how is physical > existence different from mathematical existence? > > > Two different meanings of the word 'exist'. Physical existence relates to > physical objects; mathematical 'existence' relates to mathematical ideas. > > If you think these are the same thing, then show me the conscious being > that exists independently of any physical substrate. The fact that you > appear unable to do this, and no-one else has ever done it either, is > overwhelming evidence that no such non-physical conscious beings exist. > > Until you can point to a difference that makes a difference, between physical existence and mathematical existence, and no-one else has ever done it either, I see no reason to accept that "physical existence" is somehow more special, or more capable than mathematical existence. Jason -- 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 http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
