>
> Russell Standish wrote:
>
> > [...] Paraphrasing your thesis, COMP is the
> >assertion that "you can survive the replacement of your brain by a
> >digital machine" at some level of replacement. I am reasonably
> >comfortable with what you mean by survive in this instance. I outlined
> >a possible subsitution mechanism whereby the brain is replaced by
> >analogue machines, which I don't doubt will allow survival. One can
> >then replace these analogue devices by digital ones, simply by
> >discretising the analogue quantities in a suitably fine way. Note,
> >that there is still instrinsic randomness in the behaviour of the
> >neurons, which can be discretised also with digital devices.
> >
> >I then asked you whether by digital device, you meant a "Universal
> >Turing Machine". This is where I part company with you, as I suspect
> >that (1-)randomness has something to do with free will.
Bruno wrote:
>
> In that case you abandon Church thesis. With Church thesis all
> digital device are Turing emulable, and reciprocally.
>
We obviously have different meanings for the word digital. For me,
a digital device means a discrete state device. Not all such devices
are Turing emulable. An example of one that isn't is a radioactive
source, couples with a Geiger counter, plus a simple counter such that
when a radioactive decay is detected, the state of the counter is
output, and then the counter reset. This device generates true random
numbers according to a Poisson distribution.
This is not abandoning the Church thesis, which is that there is a
distinct class of computations that are accessible from all universal
computers, and that a Universal Turing Machine is a model of such a
universal computer.
Obviously, there is a well defined subset of digital devices that are
Turing emulable. Why not call these Turing emulable devices to avoid confusion?
Bruno wrote:
> I'm afraid I don't see how 1-randomness is related with free-will.
>
> Suppose you are annihilated at some place and reconstituted in
> three different cities: A B and C. You know that you are the
> subject of that experience and you try to concentrate yourself,
> 'exercising your free-will' to be the one reconstituted in A.
> I suppose that the right level of substitution has been choosed.
> Then, although the one reconstituted in A will tell me: "you see
> my free will has worked out", I, as a computationalist (here) will
> say to the A-you: let us hear what the B-you and the C-you will
> say. And of course they will at least appear to be less sure
> they free-will has work.
> Unless, like Niklas has suggested, the B-you and the C-you will
> be so much disappointed that they will become zombie :-)
>
Firstly, free will is a 1-phenomenon. It is a category mistake to
attempt to understand it from a 3-person point of view. From the
3-person point of view, each of A, B and C will think they have chosen
the city of their destination (assuming you have set up the experiment
above so that the person has a choice - which seems unlikely given
your description above).
More importantly, we each have the possibility of chosing what to
observe. We can chose what aspect of the universe we want to observe
(ie whether I walk into your contraption in the first place or not!)
> You are consistent because you are willing to accept zombie.
> But that is a too big price for me.
Tell me the existence of zombies is too high a price to pay? Is there
some pseudo-paradox I am unaware of?
>
> Then you must explain me what is not turing-emulable in the proteins.
> You are slipping dangerously into Penrose-like non computationalism
> again here!
Whether a synapse conducts or not is a statistical process that can
never be emulated completely accurately. Brain processes appear to be
chaotic, magnifying the effect of these statistical variations. It
hasn't been established whether these statistic effects hinder the
operation of the brain, or are essential to the brain's creativity and
free will. For COMP to hold, you had better hope the former is true.
In a real computer, the random variations due to electron statistics
(Shot noise??), stray electromagnetic fields and consmic rays are
suppressed by deliberate engineering so as to approximate the ideal
computer (Turing machine) as best possible. There are no such
constraints for the brain, which is merely "engineered" by natural
selection to work.
>
> >Now, you are saying that the level of substitution implied in COMP is
> >running the whole plenitude on a computer - Schmidhuber style. How
> >does this relate to substitution of analogue brains by Turing machines
> >within the individual observer world? It seems to me a case of chalk
> >and cheese - two things that have nothing to do with each other.
>
> This is really what the UDA explain. I remember that in one of the post
> you were adressing to me, you ask me to explain the white rabbit
> problem and it is fair enough because I have been rather short in
> my explanation of it (cf PE-omega in the list).
>
> See below. I prefer first to answer your last remark to prevent
> a misunderstanding concerning the relation between Schmidhuber's work
> and mine.
>
> >It seems to me (although I haven't followed you argument to the nth
> >degree), that you are claiming in your thesis that
> >COMP=>Schmidhuber. That may be true, however, I would very much doubt
> >that Schmidhuber=>COMP. You haven't advanced a poof of this.
>
> I give you two proofs.
>
> Remember that by COMP I mean there is a level of description of my
> "generalized brain/body" such that I survive a digital substitution of my
> "generalized brain" at that level.
> Note that Digital = Turing machine, with Church thesis.
> (To get the full power of Church thesis I accept also a minimal
> amount of arithmetical or mathematical platonism).
>
> By definition my "generalized brain" is the portion of the universe
> (if that exists) which is necessary to emulate to make my
> consciousness exists.
>
> 1) First Schmidhuber clearly believes in a stronger version of comp,
> as he told us:
>
> <<According to the computability-oriented view adopted in this
> paper, life after death is a technological problem, not a religious
> one. All that is necessary for some human's resurrection is to record
> his defining parameters (such as brain connectivity and synapse
> properties etc.), and then dump them into a large
> computing device computing an appropriate virtual paradise.>>
>
> This is at the end of his paper. He does not emphasize on it, but
> clearly he believes in the existence of a level of substitution.
> Of course I explain and insist that it is both a technological
> problem and a religious one. Comp is not provable as self-duplication
> experiments illustrates. It need some act of faith.
>
Fair enough. However, I interpreted this as some extra piece of
"religious" writing that didn't follow formally from the preceding
paper. In this discussion, we don't decide things on the basis of
faith, but rather by reason and quality of argument.
> 2) But even if you forget he is telling us that explicitely
> you can derived it from the rest (non philosophical part) of
> his paper. Indeed, suppose comp is wrong, then there is no level
> of substitution such that I survive ..., then the universe or
> multiverse cannot be computable or turing-emulable and the
> 'great programmer" will never generated it (because I belong to
> it). Schmidhuber's approach would not even be a plausible
> candidate for an everything theory at all in that case.
>
I believe this line of argument is a travesty of the word COMP. Let me
start by outlining the picture I have of what Schmidhuber's Plenitude
implies (taken from my Occam paper).
i) There exists (Platonically perhaps) all possible computations.
ii) The ensemble of all consistent FASes is contained within this
plenitude. The members of this ensemble have higher measure than the
others by means of the Universal Prior. Furthermore, an even vaster
number of computations are indistinguishable from the c-FASes by a
finite observer.
iii) Assuming two propositions about conciousness (Time and
Projection/Selection) and Linearity, the anthropically viable FAS is
given by the QM multiverse.
iv) Within the QM multiverse, each observer observes a universe, with
physical laws compatible with QM. However, QM does not imply the
physical laws, nor does it imply observers. The physical universe we
see is an interpretation i.e. the MWI :)
Now, when you say I physically survive subsitution, I understand you
mean a subsitution done within level iv) - ie you actually replace my
physical brain with something. I don't expect you to change the
universe altogether. If you create another computation in the
Schmidhuber ensemble, with identical results, the if I had a terminal
brain tumour in the orginal world, I would still die in the copy (ie I
don't survive!).
>
> Note also that COMP => Schmidhuber is ambiguous, because
> Schmidhuber postulates there is a (computable) universe.
> I do not. (the existence of such a computable universe
> follows from comp only in the case my "generalised brain" is the
> "entire universe").
>
> ***
>
> The Universal Dovetailer Argument. (UDA)
>
> UDA is a proof that: COMP entails REVERSAL physics/psychology.
>
> The reversal will be be epistemological: the branch "physics"
> will be a branch of machine's psychology, and ontological: matter
> will emerge from consciousness, in some sense, hopefully clearer
> later.
>
> Indeed such a reversal will change the meaning of term
> like "psychology" and "physics" and the meaning is given ultimately
> by the proof itself. By 'proof' here, I mean argument which either
> should convince you, which means you are the only judge (no
> authoritative argument) or you should find an error.
> Of course if you belief that the REVERSAL
> is an absurdity, you are free to interpret the proof as a
> refutation of COMP (like Gilles Henri, BTW are you still here Gilles?).
>
> COMP is the hypothesis that there is a level such that I
> survive a digital functional substitution of my generalised body/brain
> (see above)
> made at that level, + Church Thesis (digital = turing) + Arithmetical
> Platonism (= the belief that arithmetical propositions obeys
> classical logic, and this independently of my own cognitive ability).
>
> To sum up: COMP = \exists n SURV-SUBST(n) + CT + AR
>
> Note also that I'm assuming a minimal amount of folk psychology (FOLK)
> without which such an enterprise would be meaningless. It is the
> minimal amount of psychology to understand that you or someone else
> could, in some situation, accept an artificial-digital brain graft,
> and to understand the intuitive difference between first and third
> person. (See below).
>
> (the modal 'chapter 5' of my thesis can be interpreted as an
> attempt (at least) to eliminate FOLK by substituting it by the
> godelian provability logics and its thaetetical variants).
> But the real goal of the chapter 5 is to make the derivation of
> physics real and concrete.
>
> To make the reasoning easy I introduce supplementary hypotheses.
> I will eliminate these hypotheses in due course.
>
> a) NEURO: The neurophysiologist hypothesis. This is a supposition that
> the level of substitution is high, or that my generalised brain is
> my biological brain (the one in my skull) relevantly described at the
> molecular level (let us say).
As I stated above, I do not understand the meaning of COMP unless it
is identical with NEURO.
>
> b) CU: there is a Concrete Universe, whatever it is. This is need
> for the decor.
>
> c) CUD: there is a Concrete running of a UD in the concrete universe.
>
> d) 3-locality: computations are locally implementable in the
> concrete universe. That is it is possible to separate two
> implementations of two computations in such a way that the result
> of one of these computations will not interfere with the result
> of the other one. Computations can be independent.
> More generally the result of a computation is independant of
> any event occuring a long way (out of the light cone) from that
> computation.
>
> e) Conceptual OCCAM razor. I will not insist. That should be easy
> for many-worlder. The movie-graph argument in my thesis is really
> an elimination of occam razor. See also Maudlin's paper.
> We talk about that in the discussion list (key word: Maudlin,
> movie, crackpot).
>
> The proof. (Apology for those who 'knows').
>
> 1) By COMP and NEURO you survive with an artificial digital (turing
> emulable, with TC) brain. OK? (CU is used implicitely).
>
> 2) By COMP and NEURO you survive classical teleportation. This
> follows from 1) where the building (reconstitution) of the brain is
> done a long way from the 'reading device' and the annihilation of the
> original body. (CU is used implicitely).
>
> 3) By COMP and NEURO (and implicitely CU, I will not mention it again)
> you survive teleportation with a delay. After the annihilation, your
> body and brain description is keep intact during one year, and then you
> are reconstituted. An important point is that you (from your first
> person point of view) will not see the difference with the simple
> teleportation case (case 2). But an exterior observator (third person)
> will see the difference. Indeed for him the delayed teleportation
> last one year.
>
> 4) You are teleported from the center of the galaxy to its border.
> At the opposite border a star explodes. This changes nothing: you still
> survive. This follows easily from 3-locality.
>
> 5) You are teleported from the center of the galaxy to its border.
> At the opposite border you are reconstituted. (For exemple the scanned
> information has been send in opposite direction from the center of
> the galaxy, and reconstituting machines has been put on the edge of
> the galaxy). You still survive, by COMP and 3-locality.
>
> 6) You are duplicable. (Direct consequence of 5).
>
> 7) Although your surviving does not depend on the faraway events,
> from the first person perspective the event "I survive at the
> left edge (let us say) of the galaxy" could depend on the faraway
> other reconstitution. The duplicability entails first person
> indeterminisme, although everything is determinate for a third
> person. (It is really the computationalist 3-determinateness
> which entails the computationalist 1-indeterminateness).
>
> (exercise: show that the duplicability entails the unprovability
> of COMP. Hint: consider teleportation without annihilation of the
> original, with a delay, applied to a non-computationalist)
>
> 8) You are 'read' and annihilated in Brussels and the information
> is send to Washington and Moscow. You are reconstituted at Washington
> and the information is keep intact at Moscow during one year. Then
> you are reconstituted at Moscow. (Duplication with assymmetric
> delay). The point is the following: whatever the way you choose for
> quantifying the 1-indeterminisme in the symmetric duplication, you
> must quantifify in the same manner the assymmetric duplication.
> This follows from COMP and 3. The first person cannot be aware of
> the delays.
>
> 9) There is also a form of 1-non-locality. Although your surviving
> does not depend on faraway events, your expectation of personal
> experience does depend on faraway events. Here also, it is the
> strict 3-locality which entail the 1-non-locality.
I don't understand this point. However, maybe it is not important.
>
> 10) Here is an old argument you can find in all idealist school
> of thought (Hindouist, Boudhist, Platon, Descartes, Berkeley, etc.)
> It is based on the notion of dream, but today it is more easy
> (especially with COMP)
> to convey it with the notion of virtual reality. The point is:
> For any neigborhood and any time interval, you can build a computing
> machine simulating that "space-time" at such a level that a first
> person will not be able to see any difference.
> (The computing machine preserves the relevant counterfactuals).
> Roughly speaking a first person cannot
> distinguish 'real neigborhood' with virtual (digitally simulated)
> neighborhood (for all level 'below' its own substitution level).
>
> 11) To sum up: the way you quantify the indeterminisme is independent
> of the time, the place and the nature (real/virtual) of the
> reconstitution.
>
> Note: the indeterminism is pure 1-indeterminism. Nevertheless, by
> duplicating entire population, the indeterminism can be made
> third person 'verifiable' inside each multiplied population. This
> leads to what I call first person of the plural indeterminism.
> (I would like to know a better english expression for that!).
I'm not sure what this point means either.
>
> 12) A Universal Dovetailer exists. (Extraordinary consequence of
> Church thesis and Arithmetical Realism). The UD simulates all
> possible digital devices in a quasi-parallel manner).
>
> (Adding a line in the code of any UD, and you get a quasi-
> computation of its Chaitin \Omega number).
>
> 13) So let us assume CU and CUD, that is let us assume explicitely
> there is a concrete universe and a concrete running of a UD in it.
> This need a sort of steady state universe or an infinitely expanding
> universe to run the complete infinite UD.
> Suppose you let a pen falls. You want predict what will happen.
> Let us suppose your brain is in state S at the beginning of the
> experiment. The concrete UD will go to that state infinitely often
> and compute all sort of computational continuations. This is
> equivalent to reconstitutions. It follows from 11 that your
> expectation are undetermined, and the domain of the indeterminism
> is given by the (infinite) set of reconstitutions. To predict,
> with COMP, what will happen you must take into account all
> possible histories going through the state S of your brain.
> And here clearly the NEURO hypothesis is not used. Even if your
> real brain state is the state of the actual concrete universe,
> with COMP that state will be generated (infinitely often) by the
> UD. Same reasoning if your brain state is the quantum state of
> the universe, so the reasoning works even if the brain is a
> non local quantum object (if that exists). So the physics is
> determined by the collection of your computational continuations
> relatively to your first person actual state.
See my heirarchy above. COMP \equiv NEURO. One's expectations are
constrained by the laws of the QM multiverse. Within that, naturally
there is 1-indeterminism. Not all brain states are reachable by
computational continuations from a given state.
>
> 14) If 'that' physics is different from the traditional empirical
> physics, then you refute COMP. But with COMP you will not refute
> COMP, isn't it? So with COMP you will derive the laws of physics,
> i.e. invariant and similarities in the 'average' continuations of
> yourself (defining the measure on the computationnal continuations).
Why should apriori COMP not refute COMP? It would simply mean that
COMP is inconsistent - and is the basis of reductio ad absurdum.
>
> Exercice: why should we search a measure on the computational
> continuations and not just the computational states? Hint: with
> just the computational states only, COMP predicts white noise for
> all experiences. (ok Chris ?). With the continuations, a priori
> we must just hunt away the 'white rabbit' continuations.
> You can also show that Schmidhuber's 'universal prior' solution
> works only in the case the level of substitution
> is so low that my generalised brain is the entire multiverse.
>
Again, I do not know what you mean by this last comment.
> 15) Once you explain why arithmetical machines are statistically right
> to believe in physical laws without any real universe, such a real
> universe is redundant.
> By Arithmetical Realism and OCCAM razor, there is no need
> to run the concrete UD, nor is there any need of a real concrete
> Universe.
> (Or you can use the movie graph argument to show that a first
> person is not able to distinguish real/virtual/and *Arithmetical*
> nature of his own implementations, and this eliminates OCCAM.
>
> QED
Fine - I have no problems arithmetical realism. The problem is when
you say COMP=Schmidhuber, when at first blush these appear to be
independent assumptions, and not well served by having identical
labels (which would immediately cause confusion).
Incidently, I believe physics is dependent on psychology, however in
rather a different fashion. For example, time is a psychological
concept, it comes from the postulate that time is required for
conciousness. Much of the rest of physics is similarly anthropically
determined. This is really the argument I outline in my Occam
paper. Nevertheless, it relies on Schmidhuber and/or Tegmark
construction, which as I have repeatedly stated, seems to be
completely independent of the COMP assumption as you've stated it. I
was hoping for a transparent explanation of why you *believe*
COMP<=>Schmidhuber.
>
>
> 16) Oh la la, I get tired. I'm sure I have forget things. I
> would appreciate any comments, especially skeptical one.
>
> The 'philosophical' proof really stop here. It is not a
> derivation of physics from the psychology of machine, it is
> a proof that physics MUST be derived from the psychology of
> machine OR COMP IS FALSE.
>
> Later I will show you how to eliminate the FOLK psychology
> assumption, by substituting folk psychology by the
> godelian provability logics and 'simulating' the first and
> third person variants with the Thaetetical variations...
> ... and I will show how, by simulating the UD by the
> Sigma_1 arithmetical sentences, the arithmetical version
> of the present proof leads naturally toward an
> arithmetical version of quantum logic (almost).
>
> With an unexpected gift : a theorisation of the non
> communicable part of the theory.
> Explaining qualia as uncommunicable part of the observable.
>
> This will also show that George Levy is valid in his recent
> answer to James Higgo :-)
>
> Am I dreaming ?
>
> Have a nice weekend,
>
> Bruno.
>
----------------------------------------------------------------------------
Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 6965
Australia R.Standish.domain.name.hidden
Room 2075, Red Centre
http://parallel.hpc.unsw.edu.au/rks
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Received on Sun Jan 16 2000 - 18:29:29 PST