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
abstraction. 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.
> > 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
> > retained.
> > 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
> > spring-
> > 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
annihilation. In fact, by saying 'yes' to the doctor, aren't you
expressing your faith in the need for a physical instantiation?
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
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.
> > A
> > 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? Haven't I heard you say that QM is Turing
emulable, just not in real time? 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.
> > 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 :)
> > 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.
> > 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.
> > and
> > 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.
>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.
>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. We need
brains. (Zombies, brains, I sometimes feel we're in a very high brow B-
grade movie here). 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, 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. 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. Even
you Bruno would probably balk at a brain removal, even though your
supervention theory renders it otiose.
> > Sure comp+phys forces us into absurdity,
> > but the absurdity has already been accepted, and the MGA adds nothing
> > new.
> '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. 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. But a Popperian falsification
is extremely difficult, 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!
> 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.
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