Bruno Marchal writes:
> Le 03-janv.-07, à 16:36, Stathis Papaioannou wrote (in more than one
> posts) :
>
>
> > Maudlin starts off with the assumption that a recording being
> > conscious is obviously absurd, hence the need for the conscious
> > machine to handle counterfactuals. If it were not for this assumption
> > then there would not have been much point to the rest of the paper.
> > Actually, Putnam and Chalmers also think that the idea of any physical
> > system implementing any computation is absurd. I am not sure of
> > Mallah's position (he seems to have disappeared from the list after I
> > joined), but Hal Finney seemed to give some credence to the idea, and
> > outside the list Hans Moravec and Greg Egan seem also to at least
> > entertain the possibility that it is true. I would be interested if
> > anyone is aware of any other references.
>
>
> Hans Moravec has defended in this list indeed the idea that even a
> teddy bear is conscious. You could perhaps search in the archive my
> reply to him. I will try to sum up what I think about this, but other
> things need to be clarified, perhaps.
>
>
>
> > Although you have clearly stated that the two ideas - consciousness
> > supervening on all physical processes and consciousness supervening on
> > no physical process - are completely different I think they are
> > related in that in both cases matter is irrelevant to consciousness,
> > ...
>
>
> If consciousness supervenes on all physical processes a case can be
> made that matter could be relevant for consciousness. (I see Peter
> Jones makes a similar remark).
Except that you could say the same for the Maudlin example, in which it is shown
that conscious can differ in two objects which do not differ in physical activity: it
does not strictly show that physical activity (or more generally, matter) is unnecessary,
just that the usual definition of supervenience does not apply.
> > ... and we may as well say that what is important is computation as
> > platonic object, not its accidental correlation with (putative) real
> > world processes.
>
>
> That's the point indeed. A consequence. Not something I assume. You put
> it right below.
>
>
>
> > They are also closely related in that the main argument against them
> > is "that's absurd". A second argument against them is also the same:
> > the difficulty explaining why we don't suddenly find ourselves in
> > "white rabbit" universes.
>
>
> My point was to show that comp transforms partially the "mind-body
> relation" problem into an explanation of why such white rabbits are
> rare. The non triviality of the mathematics of computers gives more
> than a hint: in acomp (arithmetical translation of the UDA) we can
> already show how a "quantum like quantization" occurs for the
> observations having "probability one". I will insist on this later
> perhaps. I must find a way to explain more the math without frightening
> the inumerates :)
> (Academically it has been the inverse: I had to motivate the mind-body
> problem to mathematicians who are known to be generally allergic to
> anything just looking like metaphysics. This has been far more
> difficult!).
>
>
>
> > Throwing out comp throws out physical supervenience as well, so it can
> > eliminate the problem. Keeping comp and throwing out physical
> > supervenience is the tricky thing.
>
>
> I don't see why throwing comp throws out physical supervenience. On the
> contrary, if my reasoning is correct, throwing comp is even the only
> way to keep a physical supervenience, for example by asking for a non
> computational physical process (like Penrose BTW but for very different
> reasons).
> Keeping comp we just have to throw out physical supervenience. It can
> look tricky because, we are used to associate a particular mind/person
> with (what we see as) a particular body. My opinion is that this is
> just an aristotelian prejudice. Technically there is a priori no
> problem (except the mathematical rarity of the white rabbit) given that
> a computational supervenience thesis remain available. Consciousness is
> associated with the infinity of equivalent (non distinguishable)
> mathematical-computations. Time and space appears then to be internal
> relatively stable constructions.
You take comp and supervenience as two separate theories, but I would bet
that most computationalists take them as a package deal. This is what I mean
by "standard" computationalism. It is not to say that comp and supervenience
cannot be separated, but some people are just going to respond "that's absurd".
> >
> > I wonder if we are talking about the same thing, because it doesn't
> > seem to me that an empirical proof is needed to show that any physical
> > process could be seen as implementing any computation.
>
>
> This is not obvious at all. You need both empiry + a physical theory
> about that empiry, just to say that there is a physical process
> implementing if only one computation (to say nothing about all
> computations).
All you need is one physical process. If consciousness is in no way dependent on the
details of this physical process, then the actual physics is irrelevant. Do you see how,
aside from one small detail, this is equivalent to saying that consciousness is not
dependent on any physical process at all?
> > For example, it is no problem if the physical process under
> > consideration lacks a sufficient number of distinct states, because
> > the one state can be reused to perform as many computations in
> > parallel as you want, in the same way as a certain value in a given
> > computer processor register will be the same in the course of
> > countless possible computations.
>
>
> But the state of the universal machine doing the computation will be
> different. If the computer comes back to an earlier state it will loop,
> and as such it will lose its universality. A state makes sense only
> relatively to a universal machine ("material" or arithmetical say)
> getting through that state.
It doesn't matter if the machine loops, because the one physical state can
map to many different computational states. Semantics is arbitrary.
> > Of course this is completely useless as far as practical computation
> > goes because to keep track of random 1's and 0's which, looked at the
> > right way, are implementing a word processing program, you need to
> > write the program and implement it on a conventional computer to keep
> > track of everything. It is like saying that a page covered in ink
> > contains any given text: true in a trivial sense, useless as far as
> > helping you write a letter goes. However, what if computation can give
> > rise to consciousness?
>
>
> A computation is not just a collection of states. It is better
> described as an ordering of discrete states relatively to a (universal)
> machine computing producing those states. The "produce" here does not
> to have to be a temporal or material processes, but can be described in
> term of atemporal arithmetical relations. That is why we can expect non
> trivial probabilities for going to one state to another.
But if you consider a physical computer the actual states corresponding to the
steps of the computation can be arbitrary. They will be ordered in a certain
consistent way, so we can utilise the machine, but that is just a practical
requirement. The natural number 3 does not have to be written as "3" nor
even as "III"; it could be written as "II" on a Wednesday, "IIII" if the moon
is full and "I" the rest of the time. This has no effect on the platonic object 3,
but it does affect our ability to communicate and do arithmetic unless we keep
track of the notation. Similarly with a computation, we need to be aware of the
meaning of the states on a physical computer in order to use it, but our awareness
of the computer semantics does not "create" the computation or imbue it with
consciousness (if computations can be conscious) any more than our awareness
of mathematical notation creates the number 3.
> > This would be like saying, what if a particular page of text were
> > conscious? You would still need to remove all the unnecessary ink in
> > order to read and perhaps interact with the text, but if you just left
> > it alone it would still be conscious, dreaming away on the black page.
>
>
> OK, but in that sense, assuming also a very speculative sort of
> physical infinity, all computations will be there in a trivial sense:
> all pieces of that paper contains not only UD* but the whole of
> platonia (a non comp object). Without that infinity speculation I could
> argue that most physical theories today will justify that among the UD
> accessible states only a finite numbers of them will be accessed. That
> is literaly nothing compared to what the whole of UD* needed for both
> consciousness and then physical laws (assuming comp).
> Perhaps you believe in physical real number (almost all real number
> contains arithmetical truth coded in a non readable way). If physically
> real numbers exist (why not, they don't really exist in loop gravity,
> but they do exist in string theories), then any analog (non static)
> machine embed arithmetical truth (much more than all computations) in
> all of its activity. But now, it can be shown that such machine are not
> turing universal: there are many problem that such machine cannot even
> address. This is not an obvious result. Tarski showed it by proving
> that the first order theories of the reals can be made complete and
> decidable (and are thus logically poorer than Peano Arithmetic).
> This can also be explained in term of Polynomial Equations with integer
> coefficient. That is, equation like the following:
>
> 3xyzt + 24yx^3 -7x^45 - 4u - 12 = 0
>
> If the variables or unknown x, y, z, t u belong to the reals, it can be
> shown (by Sturm + Tarski) that there is an algorithm capable of finding
> the solutions; but if you ask that the variables are natural number or
> integers then there is no such algorithm. If this seems weird just
> think about Fermat which is trivial on the reals and very difficult
> with the natural numbers (but recently solved by Wiles & Co.).
>
> If you want, the problem with the "black pages" is that there is no way
> (or all ways!) to distinguish (internally or externally) the difference
> between an "incarnation/implementation" of the number 1 and the number
>
> 1,
> 000000000000000000000000000000000000000000000000000000000000000000000000
> 0000000000 ... 000100000....
>
> This changes once you add the sinus function. Trigonometric or periodic
> functions are a way to reintroduce the natural numbers in the frame of
> the reals (by sinus(2PIx) = 0 for example). But to show that the black
> page implements the sinus in a genuine computational (even in not
> external user friendly way) is again not obvious and presuppose many
> physical things. We can come back on this later perhaps.
Why can't the black page contain everything that can possibly be written, i.e.
it can be a superposition of an infinite number of pages with an infinite amount
of ink?
> > One argument against this idea is that it is not enough to leave the
> > computation (or the text) hidden in randomness, because it is only
> > through interaction with the environment that consciousness manifests
> > and only conventional brains and computers can interact with the
> > environment. But this excludes the possibility that the conscious
> > entity is dreaming or interacting with a virtual reality, isolated
> > from the substrate of its implementation due to the impenetrable
> > randomness.
>
>
> OK.
>
>
> [Stathis wrote also:]
>
> > Peter Jones writes:
> >
> >> > SP: 'using the term "comp" as short for "computationalism" as
> >> something
> >> > picked up from Bruno. On the face of it, computationalism seems
> >> quite
> >> > sensible: the best theory of consciousness and the most promising
> >> > candidate for producing artificial intelligence/consciousness'
>
> >> What Bruno calls comp isn't standard computaitonalism, it has
> >> an element of Platonism.
> >
> > Standard computationalism involves the idea that consciousness can be
> > captured by a computer program running on a computer. Bruno keeps the
> > first part but challenges the second, suggesting that the idea of the
> > physical process in the computer actually causing the conscious
> > experience is flawed, as per Maudlin's paper. Thus he does not begin
> > with the idea that conscious computations exist as Platonic objects
> > (although I think he did suspect this all along) but ends with it as a
> > conclusion from examining the claims of standard computationalism.
> > Always risky to summarise someone else's ideas when they're watching,
> > but perhaps Bruno could comment if I have it wrong.
>
>
> No you are right. By comp I really mean "standard computationalism". It
> is equivalent with the "saying yes to the doctor who proposes some
> artificial digital (generalized(*)) brain substitution for some level
> of description". To make the "digital" condition transparent and
> machine or formalism independent, I put Church thesis in "comp". Then
> the arithmetical realism (platonism) is just the acceptance of the
> excluded middle principle (A or ~A) for the arithmetical propositions A
> (actually I need only the Sigma1 one, those with shape A = ExP(x) with
> P decidable).
> It is the platonism of the usual working classical mathematician.
> So comp is really "standard computationalism", probably made a little
> more precise than usual. The idea that Matter (primary matter) has no
> role at all in science and consciousness is just an (admittedly non
> obvious) consequence of standard comp (cf. UDA). Of course I did
> suspect this all along. I am also glad with it in the sense than
> physicist does not presuppose primary matter except in a meta-heuristic
> way when they want to explain their subject matter without digging too
> much in the theoretical interpretation problems. But most physicist
> does use, without any problem of conscience, the excluded middle
> principle on arithmetical propositions. In acomp (arithmetical version
> of comp where it is explained "how" to derive the physical laws from
> the number theoretical truth) I don't even need any "ontological"
> platonism: I interview at the start machine who "believes" (= prove
> here) the excluded middle principle, that is I am using a more
> epistemological weaker form of "platonism". But for the UDA (which
> explains *why* we have to derive the physics from the number) you have
> to accept that for all natural number i and n, either Fi(n) is defined
> or Fi(n) is not defined. The UD itself would have no sense in the
> contrary case. Fi = the ith one-variable program in an universal
> enumeration of all partial computable function (cf Church thesis).
>
> (*) The concept of generalized brain (the portion of whatever is needed
> to be Turing emulated so that my consciousness is locally recreated) is
> necessary to prevent the Colin Hales (but see also Johnson Laird in the
> literature) move consisting in saying that "the environment" plays a
> role in my consciousness: if that is the case put the environment in
> the brain (by definition). If the environment is both needed and not
> turing emulable then comp is just *already* false.
>
> Bruno
>
> http://iridia.ulb.ac.be/~marchal/
Stathis Papaioannou
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Received on Thu Jan 04 2007 - 23:56:00 PST