On 31 Dec 2011, at 03:37, Pierz wrote:

On Dec 31, 4:36 am, Bruno Marchal <marc...@ulb.ac.be> wrote:
On 30 Dec 2011, at 03:10, Pierz wrote:

This thread has been extremely helpful to me in terms of getting to
the heart of this problem and the whole issue of supervenience - thank
you Joseph for your clarification of the meaning of the term and for
your succinct and clear summary of the MGA, and to David for the nice clarification of the 'qua materia'/'qua computation' distinction. But
I have yet to see why the MGA proves that consciousness can't
supervene on abstract computation +  concrete implementation.

I would say it does. If you agree with my answer to Russell on
supervenience, that should be clear.
Indeed you can see MGA as proving that IF my consciousness supervenes
on abstract computation + concrete implementation then my
consciousness supervenes on abstract computation only. Concrete
implementations become explainable in term of relative abstract
implementations (kind of things you can easily translated in term of
the phi_i and the W_i, and from that, in pure arithmetic).

I can
see that Joseph's refutation misses the mark because the issue is that
the replaying of a recording, whether on a screen or within the
original mechanism, performs no computations. But why cannot the
materialist/computationalist merely counter that Alice *is* a zombie
during the playback of the movie, because the required instantiation
of  a computation is absent?

I tend to agree. but most people will not because they define the
zombie explicitly by an entity behaving like a human *in all*
situations, so that whatever they are, they handle the
counterfactuals. But accepting your sense of zombie, that I am
guessing, I am OK for saying that Alice, or any appearance of a person
in a movie can be seen as a sort of zombie.

OK, yes my terms are sometimes less than rigorous, sorry about that. I
suppose I just mean "not conscious" in this instance. I do wonder
though (as an aside), whether you couldn't regard a recording as
'crystallising' in a sense the consciousness it records. If a
consciousness is abstract, then the recording continues to represent
that abstraction in the same way a body/brain represents the

Yes. The film does encode comp state, and as such can be used to reimplement the person in a boolean graph, making possible the recovery, not of the consciousness (which is in Platonia) but on its relative ability to manifest itself relatively to you.

I heard recently about a condition called Transient
Global Amnesia in which people temporarily lose the ability to record
new memories beyond say the last minute, and forget years of their
history. In such an event, these people behave repetitively, much like
a recording (a 'broken record'), as if the same conscious state is
recycled over and over. Are they zombies? No, and you can easily
enough say they are just a computer stuck in a computational loop,
but  if consciousness is abstract, then a repeated calculation
represents the same conscious state, and the physical thing performing
the calculation is just a type of window onto that abstraction, just
as the recording is a window onto the abstraction. In that sense a
recording might be conscious, in the same way the person in the mirror
is as conscious as the person looking into it.

Yes. In that same way, and that why we will have to abandon the idea that consciousness supervene on the physical, and accept the idea that the physical supervene on consciousness, even if locally it has to look like the contrary, for reason which can be explained and tested.

Sure, he is committed to consciousness of
the machine if the physical activity is identical, but in the playback
of the film, the activity is not identical, since the connections
between logic gates are broken and/or overridden by the *projected*
activity (be it 'lucky rays' or the film).


Although the sequence of
firings in the network is the same, the causal connection between
firings is removed - indeed this is the point: no calculation is being
carried out.


But a sequence of firings in a logic network is not the
entirety of that network's physical activity. Or rather, the physical activity of the sequence is not sufficient to define its activity as a computation. That requires the casual connection between firings to be

Imagine a domino computer. I can't remember where I heard this first
(maybe on this list somewhere), but we can imagine a network of
loaded dominos that are set up to spring back upright after a certain
time. By setting up rows of such dominos in a clever fashion, we can
use it to perform calculations. Let's say we perform a calculation
with a boolean output - either a domino at the end falls or it
doesn't. If we set up such a domino computer and push the first
domino, we initiate a causal chain reaction that performs the
calculation we have programmed it for. Now imagine we disable the
causality by gluing the dominos upright. Now imagine we have a set of instructions telling us to lower and raise dominos in such and such a sequence. Our instructions happen to tells us to raise and lower them in exactly the sequence they would have if they had simply been pushed without the glue. This could be a random set of instructions that just
happens to be the same (as per luck rays), or a description
(recording) of a previous actual run of the computer (as per movie
graph). This is a restatement of the MGA scenario. In that case, the
casual interaction between dominos has been removed, but the sequence
of 'firings' in the network is retained.

OK. This should help to get the conclusion that consciousness is not
supervening on the physical behavior of the dominoes, but on the
abstract relationship which makes them doing a computation. Given that
most people agree that consciousness is not a material substance, we
have no problem to attach consciousness to that abstract setting,
which includes the counterfactuals by the mathematical definition (of

Right, but of course by that definition, combined with the definition
of supervention, consciousness would not be changed if you removed the
dominoes altogether. You are happy with that, but most people still
feel the need for  a brain and don't expect to survive its

This is because evolution makes us taking our local neighborhood as important. But from a scientific point of view, invoking a real brain is not an explanation. It is just a methodological (instrumentally useful) gap-filling type of pseudo-explanation, and it makes the mind- body problem insoluble.

In fact, by saying 'yes' to the doctor, aren't you
expressing your faith in the need for a physical instantiation?

Sure. But I don't need a primitive physics for that.

Otherwise you'd just say "No thanks, I'm off to cavort in the
arithmetical platonia. See you there for a cup of pi squared at

Lol. But the goal of an artificial brain is not just "surviving". It is used to survive with a high probability in the computations that I share most probably with my current fellows. You use it to see your grand-grand-grand-children, or to be present at the next soccer cup. The goal is to maintained stability with respect to your most probable computations.

You can say the dominoes are epiphenomena arising from arithmetical
relations in the 1-p perspective, but that would just beg the
ontological question. We are disputing the steps that allow you to
make that assertion in the first place.

Now the materialist-computationalist already believes in the odd
scenario of a consciousness instantiated by a computation in which the steps of the computation are performed in different places in time and
space - eg one step in a calculation is performed in Sydney on one
machine in 2011 and the next is performed on another in Melbourne in
2012 (local examples rather than Brussels-Amsterdam!). It is still a
potentially conscious calculation if a causal connection between
computational steps is retained.


Remove the causality from the
scenario and it becomes meaningless and absurd - otherwise
consciousnesses would arise between all kinds of  unrelated things.


bit of half written code on my computer in Melbourne could be
completed by some half written code on your computer in Sydney, even
though the computers and the programmers never interacted. And of
course, everything physical is Turing emulable, so everything physical
performs (at least trivially) calculations.

It is not clear that everything physical is Turing emulable. Neither
with QM, still less with comp.
Then it is not clear why "everything physical is T emulable would
entail that "everything physical performs calculations".
But I do agree that  "everything physical performs calculations", for
trivial reason (you can interpret everything as the output of a
trivial computation, like the constant function 1.

Sorry, puzzled. If the physical world is not Turing emulable, then
surely your UDA fails?

The fact that the physical world is not Turing-emulable does not entails that some part of it can be, like the working of a brain or of a computer. So I can be Turing emulable despite the fine grained description of the matter which makes my brain is not. And, indeed, if I can be truncated at some level, whatever I look below that level will be a sum on infinities of computations, and does not need to be computable a priori (by the global (on UD*) first person indeterminacy).

Haven't I heard you say that QM is Turing
emulable, just not in real time?

Yes, and that's weird. But QM is Turing emulable only if we emulate the couple (observers + observed), and that coherent with comp, where some observable physical features might need the entire UD*.

Anyway, it's not that relevant. The
point is, at least the classical physical processes are Turing
emulable, and the physical processes can be seen as instantiating the
calculations that would be required to emulate them. A billiard game
computes the trajectory of billiard balls.

Stephen King said something like this, and it can make sense. Personally I prefer to distinguish an emulation from identity. An emulation of program A by a universal numbers U needs an explicit coding of A in the language of U.

Consciousness would arise
between all the random motions of particles that could be regarded as
performing a calculation *if* they were causally connected. Madness.


Heart warming when you say OK like that :)

OK :)

So, given that causality is physical (even if such causality is highly
indirect), then comp-phys can argue that Alice is a zombie in the
projected film scenario because of the severance of causality between
the activity of logic nodes. The computer no longer instantiates a
physical computation and comp-phys requires both a computation and a
physical instantiation.


Personally, I think the scenario of a physically atomised computation
does comp-phys in anyway. The notion of physical activity seems
stretched beyond breaking point when we extend it to the sequence of
causes that connects the steps of such a computation. No further
reductio ad absurdum is required.

Hmm... OK. But UDA-MGA is constructive, it shows where and how physics
arises, from comp. It makes "physical" into an entire "new" (except
Plato & the Mystics) perspective. It reduces effectively the mind- body
problem into a pure "belief in body problem by universal digital
machine (numbers)". It leads to a problem in computer science and/or
Number theory.

Sure, but I'm saying you could reach the same conclusion as MGA just
from the atomised computer argument. Yet comp+phys seems to swallow
this. Maudlin does in the Olympia paper, even if it chokes just a
little on the way down. If they can do this, it seems they can make
the argument that recorded Alice is not conscious, and that physical
instantiation is still required.

Logically: yes. Epistemologically: no.

But the problem with any reductio ad
absurdum is that different people find different things absurd,

It is up to you, in that case, to ask them what are their assumptions.
In which theory they are working. Climbing up to the point where you
agree on what you disagree, which means the correspondent were not
working in the same theory.

The theory I work in is any theory in which I would survive thanks to
my ability to make my most probable environment able to emulate, or
approximate sufficiently well *some* computation. And I assume only he
math needed to make the argument in favor of Church thesis

In that case, I argue that physics becomes logically definable and
derivable (and thus necessary) from machine's theology (which concerns
the difference between what machine can justify rationally about
themselves and what is true about themselves.

seeing as comp-phys accepts the possibility of a temporally and
spatially atomised, conscious computer, so it can use the same
principle to refute the MGA.

But that kind of refutation becomes trivial, if you keep comp and the
whole UDA, where MGA = UDA step 8.

Wait on - you're saying that this type of refutation of MGA becomes
trivial if you keep the whole UDA, where the UDA includes MGA? Tut-
tut, Bruno. That is patently circular.

I should have said just using UDA1-7.

It makes primitive matter into an
epinomenon (an invisible horse). That is why I say that MGA leads to
an epistemological contradiction and not an ontological one.

I wish I understood what you mean by that.

Like a creationist who accept the theory of evolution, but will insist that only a God can create everything needed for that evolution to occur. You can always add spurious ontology. UDA (MGA) makes any use of primitive matter magical.

It is not
unlike the Bohm move in QM (selecting one branch of the multiverse).
MGA cannot refute logically such a move, but it makes it ad hoc: it
appears only as a way to NOT solve the mathematical mind-body problem.
It invents matter, it invents a mind, it invents an identity thesis,
and it stops the search of the understanding of the relationship. It
invents three problems, and solve nothing.

As I've said we're on the same team with regards to primitive
materialism. But I have sympathy for the materialists on this issue of
instantiation. After all, we need computers still, we can't rely on
the arithmetical platonia to predict the weather for us.

Again, we need brain, bodies and computer to optimize the probability of staying in the branch we share at our substitution level. And if the argument is correct, the weather and you are already in Platonia. The local relative body is needed to not jump too quickly in alternate consciousness/realities.

We need
brains. (Zombies, brains, I sometimes feel we're in a very high brow B-
grade movie here).

Well, that's not a coincidence. Good B-movies often contains deep insight, without taking themselves seriously.

You call it ad hoc, but the observation that a
computer/brain is still required, and the powerfully counter-intuitive
idea that consciousness would be unaltered by the removal of the
physical organ,

It will be statistically altered. You still need a brain to make some branch more probable than others. If you just want to surivive, you can jump out of the window, but the probability is high that you will survive in a non-comfortable state, for awhile. Indeed, that why Platonia makes brain, to look at local relative stable details.

lends the position more force than its logic alone. We
don't need to say much about matter, merely that it (whatever 'it' is)
is required in order to lend some kind of ontological status to the
abstraction of a calculation in order for a consciousness to exist.
Your admission that MGA cannot refute such a position weakens the
force of the UDA.

Not at all. We always have to do this in applied science. Applied science always use some form of Occam.

It is not necessary to accept its conclusions by
pure logic after all. Rather you must accept it on the aesthetic
grounds that it solves the mind body problem. But against that
advantage you must put the phenomenological force of materialism.

I don't think so. I see this as an advantage. It is the discovery of a realm (arithmetic, say) from which we can explain both consciousness, and see, conceptually and technically, where the laws of physics come from. We get the how and why of matter, and we get the how and 99.9% of the why of consciousness.

you Bruno would probably balk at a brain removal, even though your
supervention theory renders it otiose.

It does not. It makes it possible to converse with you and to prolongate shared experience. It makes otiose the idea that my brain is primitively physical, and it makes otiose the idea that physics is the fundamental science a priori.

Sure comp+phys forces us into absurdity,
but the absurdity has already been accepted, and the MGA adds nothing

'course, I tend to disagree with this. At UDA-7 the mind-body problem
is already reduced into a problem of a self-referential relative
measure. A pure mathematical problem (handled by AUDA or the interview
of the LUM). But UDA-7  assumes a "real" physical universe. MGA, UDA-
step-8, shows that we can eliminate that assumption. It shows that a
"real" physical universe is a read herring, as far as been used to
singularize consciousness.

Yes I do understand the UDA reasoning. I remain uncomfortable with it,
as I am with any reasoning that invokes infinities to explain finite
observations, e.g., the anthropic principle.

OK. But the anthropic principle itself is not used. A weaker Turing- tropic principle is used, and the probabilities are made local and relative.

They explain so much and
so little. I'd become much more interested in UDA if it made some
concrete predictions about what the laws of physics should be
according to this arithmetical ontology.

That's AUDA. I can explain more, but it is better to get UDA straight before we translate it in arithmetical term, to get the physics. I only got the propositional physics (logic of observable), but that's because we get hard mathematical problem (as we can expect in such approach).

But a Popperian falsification
is extremely difficult,

Not at all, in principle. You can list the comp-physics tatutologies and compare them already with the quantum tautologies. Up to now, it matches well.

and the argument can always hide behind the
intractability of burrowing that deep into the UD. Deutsch refutes the
anthropic principle on the basis of the impossibility of defining a
measure on infinite discrete sets where there is no natural ordering
principle (apologies for my lack of all the correct mathematical
terminology). I've applied that to the UDA, but you have insisted that
such a measure is possible. I hope one day to understand why!

Well, if the measure does not exist (and if that is proved) then comp is refuted. But the measure has already been found for the particular case of measure one, and this is promising, I think.

This is not nothing. It means comp is closer to Plato type of theology
than Aristotle type. It illustrates, at the least, that science has
not yet decided between Plato and Aristotle conception of reality.
Note that most atheists are much more close to Aristotle theological
metaphysics than most Christians, notably concerning the immortality
of the soul.

The notion of computation is tightly linked to the notion of universal
number, and their properties. Comp invites computer science and the
computers at the table where we debate on fundamental questions.



Thank you again for your generosity in responding to my sometimes wide-
of-the-mark arguments. It is a most mind-expanding exchange for me.
Happy New Year to you too.

The pleasure is mine. Best wishes,



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