Be assured that I still fully intend to follow the logic of UDA as 
far as I can. And I'm grateful for your frequent efforts to suggest its meaning 
in words and to explain why words alone are inadequate. I wonder if you could 
clarify your use of the term "supervene" in the context below and elsewhere. 
How can consciousness supervene on the mathematical computations that produce 
that consciousness? Is this the ultimate in self-referential authoring? Best 
    marty a.

  ----- Original Message ----- 
  From: Bruno Marchal 
  Sent: Friday, July 17, 2009 8:00 AM
  Subject: Re: Dreams and Machines

  Hi David,

  I comment your post with an apology to Kim and Marty, then I make a comment 
to Marty, and then I comment your (very nice) post.

  Kim, Marty, I apologize for my bad sense of humor. Rereading some post, I 
realize some nuance in the tone does not go through mailings. Please indulge 
professional deformation of an old math teacher ...

  On 17 Jul 2009, at 03:12, m.a. wrote:

               I appreciated this post because I'm more interested in the 
    philosophical implications (which I'm hoping to find at the end of Bruno's 
    UDA bridge to Valhalla) of these goings-on  ...than in the mathematical 
    ones. Best,

  Marty, I can understand you. At the same time, many discussion have been more 
philosophical, and the problem here, is that without some amount of math, and 
of computer science, things will look like a crackpot-like thing. It is almost 
in the nature of the subject. Big statements needs big arguments, and at least 
enough precise pointers toward the real thing.

  You can have a still more passive understanding of the UDA, if you understand 
the first sixth steps. Then for the seventh, it is enough to believe in the 
existence of universal dovetailer (itself a quasi direct consequence of the 
existence of a universal machine). 
  Then the 8th step alone can help you to have an idea why the Universal 
dovetailer is immaterial, so that physics has to be reduced to math and 
"machine psuchology/theology".
  But then, I will not been able to answer some remark which have been done by 
Stathis, Russell, Brent and some others, and which are relalted to the 
difference between a computation (be it mathematical or physical)  and a 
description of a computation (be it mathematical or physical), and this is the 
key for understanding that when we assume brain are digitalizable, eventually 
we have to abandon the idea that consciousness supervene on physical 
computations, and to accept that it supervenes on mathematical computations.
  You know, the discovery of the universal machine is the real (creative) bomb 
here. I could say that "nature" has never stopped to invent it and reinvent it, 
like with the apparition of brain, of life and the possible other many big 
  Then, it is hard to explain, without learning a bit on numbers, functions, 
sets and mathematical structures, that arithmetic, simple elementary 
arithmetic, already describes that universal thing which can't help itself to 
reinvent hitself again and again and again, and this in an atemporal, aspatial 

  Sri Aurobindo made once a nice summary:

  What, you ask, was the beginning of it all?
  And it is this ...
  Existence that multiplied itself
  For sheer delight of being
  And plunged into numberless trillions of forms
  So that it might

    ----- Original Message ----- 
    From: "David Nyman" <>
    To: <>
    Sent: Thursday, July 16, 2009 8:38 PM
    Subject: Dreams and Machines

    With Bruno and his mighty handful engaged in the undodgeable (though
    constantly dodged) task

  Well said!

    of working towards an elementary grasp of the
    technical underpinnings of COMP, and patently lacking the fortitude of
    these valorous Stakhanovites, I have been spending my time lurking,
    reading and musing. My philosophical position on possible relations
    between computation and mind has long (well before this list) been
    that it would indeed require something like Bruno's reversal of the
    'normal' relationship between computation and physics, so that mind
    could emerge in some at least comprehensible manner; certainly not -
    per impossibile - in the ghostly shrouds of the 'deus ex machina' of
    'computational materialism'. Consequently, parallel to the strenuous
    effort ongoing in the other thread, I have been wrapping my mind more
    loosely around 'interpretations of COMP-mechanics' in order to attempt
    a better personal grasp of what it might mean as a metaphysics. As
    always, I need help, so here goes for starters.

  This points to another problem I have. The UDA, and probably even more the 
AUDA, has deeply changed my "philosophy", up to a point where I think that 
philosophy and metaphysics can be handled with the doubting attitude of the 
(ideal) scientist, and that this attitude is a vaccine against the most inhuman 
aspect of "human science". But then I have reason to suggest that everything 
becomes far more clearer if we drop the expression "fundamental science", 
philosophy", "metaphysics" (unless we use them in their original greek senses) 
and come back to the expression "theology". If you want, assuming comp, 
metaphysics becomes a theology, with its communicable and non communicable 
parts. Assuming comp we can already listen to the course on machine theology 
provided by the machines.
  But then I know that I look over-provocative. 
  At the same time, I feel that this is important, because, I don't see how we 
could ever win the war against authoritative arguments and fundamentalism of 
all kinds without bringing back modesty (that is science) in that field.
  When you grasp comp, you can understand that those scientist who pretend not 
doing theology are those who take Aristotle theology for granted. (Actually 
even a simplification of Aristotle. Aristotle was more Platonist than we 
usually imagine).

    Bruno has sometimes remarked (if I'm not misrepresenting him) that
    COMP introduces us to machines and their dreams and I find this
    metaphor very cogent and suggestive. 

  You don't misrepresent me ... too much. Just that dreams is no more really 
use as a metaphor, but as a literal thing. It is a point of using digital 
mechanism, and assuming it clearly, and not just a vague mechanist intuition, 
which is already at play in all rationalist approach to inquiry.
  If someone accept an artificial heart, he/she does not got a metaphor in 
his/her thorax. It is the same for an artificial brain, and eventually for a 
purely arithmetical one.

    Certainly it seems to me that my
    present state could coherently be characterised as a peculiarly
    consistent dream - one that I nonetheless assume to be correlated
    systematically with features of some otherwise unreachable

  So you are a critical realist. A "believer" in the large open minded sense. 
  The key lesson of UDA here is that, although you are right to bet that your 
present state belongs to a consistent dream, the 'truth' (a theorem in comp) is 
that there is an infinity of consistent dreams matching your observations, and 
there is a sense in which you (first person you) actually belong to an infinity 
of them. It is the many dreams aspect of the comp theory, partially confirmed 
by the quantum empirical MW observations.

    In COMP, the 'mechanism and language of dreams' is
    posited to be those elements of the number realm and its operators
    that are deemed necessary to instantiate a 'universal TM' (i.e. one
    that - assuming CT to be true - is capable of computing any computable
    function). Given this point of departure, 

  Well the point of departure is really that I can survive with an artificial 
"physical" brain. And the result is that "physical" can no more be a primitive 
notion, and that the physical appearance has to be explained from the numbers, 
and indeed from their relative self-reference modalities. This leads to the 
arithmetical 'hypostases'.

    it follows that machines so
    instantiated would be capable of implementing any computable 'dream'
    whatsoever - including dreams instantiating yet further levels of
    machines and their dreams. With an additional dovetailing assumption,
    we find ourselves in a position to construct a sort of hyper-threaded
    layer-cake of dreaming where, from any arbitrary level, recursively
    nested dreams disappear towards infinity both 'upwards' and

  All right. Except that the dovetailing is not an additional assumption. The 
dovetailing is already there, like the primes numbers are already there, once 
you posit the sixth first axioms of (Robinson) arithmetic. Sorry for being 

    As we 'drill down' into this gateau, we are looking for emergent
    patterns of invariance representing the self-referential viewpoints of
    layers of 'dreaming machines' - their experience and their 'external

  It is good idea to put 'external reality' in quote. It is a very ambiguous 
notion. It can be the simple pure third person provable relations among the 
numbers, like it can be the first person plural emerging appearance of 
  And it can be something in between, all that can depend, or not, of our 
substitution level, and of the meaning "we" can give to words "we", "our", ...
  Obviously we do share a long and rich history.

    The lowest level of recursion that any particular system of
    dreaming requires for its instantiation is taken to constitute its
    'substitution level'. 

  I guess that I agree with what you want to mean, but I would have said "the 
highest level" level required, in the sense that there is no lowest level. In 
case of doubt, the doctor can always bet on a lowest level of comp, just to 
diminish the probability that his patient become a zombie. Of course in 
practice this will cost more money.

    Since which layer of the cake this corresponds
    to must be unknowable from the viewpoint of any level we currently
    occupy, we ineluctably take a gamble if we say 'yes' to any doctor who
    claims to know what he's about. BTW, on this topic, I would refer you
    to an interesting analogy that I append as a footnote below.

    So, what can we take 'reality' (i.e. real, as you will recall, "in the
    sense that I am real") to mean in this schema? We cannot know, but we
    do want to say that it corresponds self-referentially - in some sense
    - to the number realm, and that the true language of the dreaming
    machines therefore corresponds - also in some self-referential sense -
    to numbers and their inter-relations. This 'sense of correspondence'
    can be defined in two ways: 'truth', which is taken to correspond
    self-referentially to the unknowably 'real', and 'provability', which
    is taken to correspond to what this reality can consistently claim,
    express, or represent to itself.

  Good summary!

    This is about as far as I've got, and broad as it is, it seems to
    point more or less in the direction of a detailed research programme
    such as Bruno has outlined. 

  Well, here I disagree in the probably looking immodest claim of mine that the 
research has already be done up to the sad point that now, only math and 
physics remains. My initial goal, unless mistakes (fatal or not) has been 
attained: now we know that the "comp theology" is science, in the Popper sense 
that the "comp theology" has been shown refutable.
  What would be nice is that the Z1* logics leads to new quantum tautologies so 
that the digital quantum nature can be tested against the quantum empirical one.

    I can see that stipulations on 'reality'
    such as universal computability make implicit claims that are
    empirically falsifiable in principle, which is most encouraging.

  This is CT, and you are correct, that part of comp is also refutable. But 
this we already have good reason to believe that nature will not, and cannot 
really refute it, unless quantum mechanics is wrong in the large proportion.
  Actually, I believe that Church thesis can be proved in higher order logic, 
but this is a point I prefer to range out of the topic, because it is not 
essential, and it can lead to confusions (and it needs even bigger familiarity 
with mathematical computer science).
  The yes doctor is highly more doubtable, and the main goal consisted in 
showing that it leads to a refutable 'theology'. Indeed, like in Plotinus, both 
the sharable and non sharable part of physics is completely determined by that 

    Also, this general approach seems to me to have striking resonances
    with metaphysics such as Bohm's notions of implication and
    explication, as well as MWI.  

  You may develop. I like very much Bohm, because he is an honest inquirer. I 
appreciate him as a respectable adversary. 
  To keep his materialist philosophy he honestly posit a non-comp assumption, 
and he is not attracted at all by the MWI. But many of its intuition fit nicely 
with the comp hyp, as we can see by taking computer science seriously. Bohm, 
like many, has still a "pre-Godelian" conception of comp, so to speak. Well I 
should perhaps reread him because I don't remember how far he is a (weak) 

    Anyway - Bruno, I would be grateful as
    ever - when you have a moment - if you would tell me which end of what
    wrong stick I've got hold of this time.

  Very nice post, David. The only general but key point where I would like to 
add precision, if not insistence, is that "metaphor" thing. Einstein would not 
have been glad if people told him that energy is a good metaphor for matter, 
when all his work consists in a coherent theory (= clear refutable assumption) 
where the relations between matter and energy are described by 
testable/refutable facts. The whole point of saying yes to the doctor, qua 
computatio, is for helping the understanding that the comp assumption is not 
metaphorical and that it leads to a theory which implies the reversal that you 
are most correctly intuiting. 
  You are correct about truth and provability. You may have insisted a bit more 
on the first person/third person important , and still unsolved, to be sure, 
relationship, and the first person indeterminacy which follows. You certainly 
motivate me to explain better AUDA and its relation with UDA. 

  I am glad that Marty enjoy your post. At the same time, the point of my work 
did consist in making this utterly clear (if not shocking for those 
Aristotelian fundamentalist). Clarity in an hot field has to be technical or it 
looks too much provocative.

  Thanks for this very clear post. You have a good intuition of the ultimate 
consequences of the comp hyp, I think.


    One day a group of scientists got together and decided that man had
    come a long way and no longer needed God. So they picked one scientist
    to go and tell Him that they were done with Him. The scientist walked
    up to God and said, "God, we've decided that we no longer need you.
    We're to the point that we can clone people and do many miraculous
    things, so why don't you just go on and get lost."

    God listened very patiently and kindly to the man and after the
    scientist was done talking, God said, "Very well, how about this,
    let's say we have a man making contest." To which the scientist
    replied, "OK, great!" But God added, "Now, we're going to do this just
    like I did back in the old days with Adam." The scientist said, "Sure,
    no problem" and bent down and grabbed himself a handful of dirt. God
    just looked at him and said, "No, no, no. You go get your own dirt!"

  Cute simple story illustrating a key point that most forget. 



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