On 24 July 2014 14:50, Bruno Marchal <[email protected]> wrote:
> As I try to see if we disagree, or if it is just a problem of vocabulary, I
> will make comment which might, or not be like I am nitpicking, and that
> *might* be the case, and then I apologize.
No worries. I think some of it is just vocabulary, but we'll see.
> My problem here is that COR is ambiguous. I don't know what you mean by
> "sef-contained "computationally-observable regime".
Well, I'm sorry for having introduced yet another acronym here, but my
intention was to see if I could set out the arguments of Step 7 and
Step 8 in a slightly more "grandma" manner. So what I'm saying amounts
to a definition: i.e. that once CTM has been assumed, it follows that
observers and the objects of observation are thereafter confined
within a "computationally observable regime". And this must be true
regardless of any additional assumptions we may have at the outset
concerning what might be "doing the computation".
> It seems to me that UD* *is* such a self-contained computable/computational
> structure, and the existence of both the UD and UD* are *theorem* of
> arithmetic, which means that such a COR does not need to assume CTM
> (comp).
Well yes, but in the spirit of the UDA, I was trying to reach this
conclusion one step at a time! I'm not sure, though, what you mean by
saying that CTM isn't part of the assumption of a COR. The whole point
is that it is supposed to be "computationally-observable", not merely
"computational".
> By its very definition, the COR sets the limits of possible physical
> observation or empirical discovery. In principle, any physical phenomenon,
> whatever its scale, could be brought under observation if only we had a big
> enough collider. But by the same token, no matter how big the collider, no
> such observable could escape its confinement within the limits of the COR.
>
> I agree, but why? here a Peter Jones can say: not at all, to have something
> "observable", you need consciousness, and to have consciousness you need > a
> physical primitive reality.
But I'm already assuming CTM, so this implies the COR. If PJ assumes
non-comp, then I say "go in peace, but please give me a non-comp
argument". But perhaps he is arguing for CTM but thinks we need a
"primitively physical computer" to explain the existence of the COR.
This line of argument is what we will attack next.
> If we accept that the existence of a COR is entailed by assuming CTM, we
> come naturally to the question of what might be "doing the computation".
>
> How could that not be answered by the existence of COR, or by
arithmetic. > We know that both the programs and their execution
can be proved to exist in
> elementary arithmetic. The problem comes exclusively from the
people who > say that *a priori* the computation are not enough,
and that they need to be
> implemented in the primitive physical reality (that they can't define, but
> the point is logically meaningful until step 8).
Perhaps it wasn't obvious that my intention was to recapitulate the
arguments of Step 7 and Step 8. You see, ISTM that the recurrent
debates over these steps of the UDA are at least in part because of
ambiguities in the way people on the list have understood them (e.g.
the recent unresolved discussion with Brent about Step 8). I was
trying to re-state them with a view to helping to clarify their
essential points.
> Notwithstanding this, we may still feel the need to retain reservations of
> practicability. Perhaps the physical universe isn't actually sufficiently
> "robust" to permit the building of such a computer?
>
> To build it is not a problem, (I did it), but to run it for a sufficiently
> long time so that we have a measure problem is different.
Yes, but of course I meant to build and run it for a sufficiently long
time. My point here was to emphasise the underlying evasiveness of
arguments that avoid the reversal at Step 7. They say, in effect:
"Yes, I assume CTM and accept that it implies a COR. I also accept (on
the arguments of Steps 0-6 ) that, in principle, this implies that a
physical computer, if run for a sufficient span of time, would indeed
"capture" all conscious experiences with very high probability (i.e.
it would dominate the COR). But I don't accept that the physical
universe is robust enough to build and run such a computer and
consequently I feel justified in discounting the relevance of UD* to
any experiential probability calculus." It should be clear, if
expressed in this explicit manner, that this is an argument from
*contingency*, rather than *principle*.
> Or, even if that were granted, could it not just be the case that no such
> computer actually exists?
>
> Well, it exists like prime numbers exists. Same for his execution. Now, I
> doubt that in a physical universe we can run it *forever*.
Again - one step at a time. We've discussed this point before. One
could accept the possibility of such a computer, and even that the
physical universe were robust enough to support its running, but still
discount its actual existence. This again would be an argument from
contingency.
> Reservations of this sort can indeed be articulated, although worryingly,
> they may still seem to leave us rather vulnerable to being "captured" by
> Bostrom-type simulation scenarios.
>
> This assume also the existence of computers, and physical computers.
Yes, that is still assumed at Step 7. But it's interesting that
Bostrom gets quite close to some of the implications of UD*.
> The bottom line however seems to be this: Under CTM, can we justify the
> "singularisation", or confinement, of a computation, and hence whatever is
> deemed to be observable in terms of that computation, to some particular
> physical computer (e.g. a brain)? More generally, can we limit all
> possibility of observation to a particular class of computations wholly
> delimited by the activity of a corresponding sub-class of physical objects
> (uniquely characterisable as "physical computers") within the limits of a
> definitively "physical" universe?
>
> That problem appears once we agree that a non physical computation can be >
> as conscious as us, and that problems appears at step seven, including its
> solutions. It is because we will take all computations (going through our
> mental states) into account that we have a measure problem, which is the
> stabilization of physical laws problem. Of course after that we need to
> formulate and solve that problem mathematically, and that is what is done in
> AUDA.
But we haven't yet reached that point in the argument. One can still
set one's face against the reversal at Step 7, on the basis (however
contingent) that the implications of UD* in a "primitively physical
universe" can be discounted on the basis, in effect, of lack of
empirical evidence for its existence.
> Step 8 differs from Step 7 in
> that it seeks in the first instance to undermine the very notion that
> physical activity can robustly embody
>
> I agree up to here.
>
> *any* second-order relations above and beyond those of net physical action.
>
> Here I disagree. I would say instead "Step 8 differs from Step 7 in that it
> seeks in the first instance to undermine the very notion that physical
> activity can robustly embody consciousness or the first person
> subjectivity". I don't see why it would undermine the second or higher order
> relation.
OK, then we need to get clearer on this, as it seems to be a constant
source of ambiguity. What I had in mind here was computation which, on
primitively-physical assumptions, is a higher-order notion abstracted
(i.e. on the part of some interpreter) from the net physical action of
a system of physical tokens. In the MGA at the outset these relations
are taken to inhere in physical logic gates. In whatever tokens these
gates are implemented, their net physical action is still, at all
times, assumed to be exhaustively constrained by physical law. This
constraint is of course what allows us to show that such net physical
action could be preserved (by accident or by contrivance) even in the
case that not a single logic gate remained in its original functional
state.
Hence Alice's brain could evolve through the same physical states and
preserve the identical relation with its physical environment, though
it would no longer be plausible to claim that anything was being
"physically computed". What precisely do you intend us to conclude
from this? The original contention was that Alice's brain, when
undamaged, implemented a certain computation. It's worth
re-emphasising here that it was always the case, even at the outset,
that her overt physical behaviour could be understood exhaustively to
be a consequence of the net physical action of her brain. Nonetheless,
by assumption, we were originally justified in assuming Alice to be
conscious in virtue of the physical implementation of a specific
computation by that brain.
But, by the identical assumptions, her overt behaviour (not excluding
claims about her own state of consciousness) could quite plausibly be
preserved even after the wholesale disruption of all these putatively
computational states. Are we to conclude that despite this
preservation of behaviour she has become a zombie? But to conclude
that she is still conscious would seem to imply that this
consciousness could never have been due to the integrity of any
"physically-implemented" computation, since that has been totally
evacuated. This would seem at first blush to imply that CTM must be
false.
So your contention that "Step 8.....undermines the very notion that
physical activity can robustly embody consciousness or the first
person subjectivity" follows IFF we consider it absurd to conclude
that Alice has become a zombie *and yet*, despite everything, we still
wish to salvage CTM. This would be plausible IFF the "primitively
physical" relations that had been assumed to embody computation could
themselves be shown to derive from the much simpler *arithmetical*
relations that embody computation. But even with this stipulation, the
MGA seems still to imply that the "brain as observed" embodies neither
consciousness, nor the specific computations that underlie it. Rather,
*that* brain is a means by which such consciousness is manifested in
relation to a reality (as you are wont to say). In terms of my LCD
analogy, the "brain that we observe" is a computation at the level of
the movie, but the deeper computations that are responsible, both for
that observation and our observing of it, are at the level of the
screen.
> The problem is only for the higher order *first person* relation
> with the physical activity of the device, ISTM (It seems to me).
Then we would seem to agree here.
> If this analogy holds, at least in general outline, what
> justification, under CTM, could remain for any assumption that our own
> observations and references might "accidentally" allude to some
> "LCD-physics" postulated, mutatis mutandis, as underlying the COR? Would it
> not seem extraordinary that any such underlying physics could contrive to
> "refer to itself" through the medium of its merely computational
> derivatives?
>
> Not sure. If arithmetic can do that, why not physics?
Because with a schema based on arithmetic it becomes possible to
differentiate the level of the movie from the level of the screen. In
arithmetic, it is accepted that all "physical" references are confined
to the COR (i.e. are at the level of the movie). The screen is a
deeper level that need not (indeed, in arithmetic, cannot) be strictly
isomorphic with what is manifested at the level of the movie. So the
immediate problem with the conjunction of a primitive physics and CTM
is that phenomena at the level of the movie get conflated with those
at the level of the screen (i.e. the "brain as observed" gets
conflated with the "brain responsible for observation"). These are
hardly original insights as Plato and Kant (to name but two) have long
since pointed them out. The assumption of CTM immediately implies a
COR (or more colloquially that observed reality is a kind of
full-participation "movie"). From this point forward any notion, that
the level of the "representational device" can simply be assumed to be
isomorphic with what is represented by means of it, is unwarranted and
unjustified. Indeed, it is incoherent.
> THAT "physics" would necessarily be entirely
> inscrutable and inaccessible for reference at the level of the COR (think of
> the LCD analogy). And hence we simply would have no a priori justification
> for assuming the observational physics of the COR to be isomorphic with some
> notional underlying "LCD-physics". In fact, once having assumed CTM, we
> would have no further basis for assigning THAT physics any role whatsoever
> in our explanatory strategy.
>
> At first sight I agree here.
Nice. Well it seems that, pace vocabulary differences, that I trust
are a little clearer now, we agree. In fact, the more I think about
it, the more ISTM that the "reference problem" is the hidden Hard
Problem at the heart of physics. It is as if we maintain a sort of
primary cognitive dissonance to avoid confronting it. Since what I've
called the COR (or some kind of "virtual reality" account of
consciousness) is the default assumption in science, it must surely be
obvious that the "logic of observation" can only refer at its own
level. Hence anything we conjecture as being responsible for that
level must automatically be considered "noumenal" with respect to
observed phenomena. Yet much of physics seems tacitly to assume that
observed phenomena *refer in fact* to a "noumenon" that is essentially
isomorphic with what is observed (albeit many orders of magnitude
removed). I've rarely seen any explicit justification of why we would
suppose that to be the case, but typically if you ask for one, you get
a circular answer (e.g. in terms of evolutionary utility). But to be
satisfied with any such answer is to be blind to the fact that it must
in fact be couched entirely in terms of the COR. I guess it's hardly
surprising that any serious attempt to defend such a notion in detail
quickly runs into the buffers.
David
> David,
>
> As I try to see if we disagree, or if it is just a problem of vocabulary, I
> will make comment which might, or not be like I am nitpicking, and that
> *might* be the case, and then I apologize.
>
>
> On 23 Jul 2014, at 15:38, David Nyman wrote:
>
> Recent discussions, mainly with Brent and Bruno, have really got me thinking
> again about the issues raised by CTM and the UDA. I'll try to summarise some
> of my thoughts in this post. The first thing to say, I think, is that the
> assumption of CTM is equivalent to accepting the existence of an effectively
> self-contained "computationally-observable regime" (COR).
>
>
>
> My problem here is that COR is ambiguous. I don't know what you mean by
> "sef-contained "computationally-observable regime".
> It seems to me that UD* *is* such a self-contained computable/computational
> structure, and the existence of both the UD and UD* are *theorem* of
> arithmetic, which means that such a COR does not need to assume CTM (comp).
>
>
>
>
>
>
>
> By its very definition, the COR sets the limits of possible physical
> observation or empirical discovery. In principle, any physical phenomenon,
> whatever its scale, could be brought under observation if only we had a big
> enough collider. But by the same token, no matter how big the collider, no
> such observable could escape its confinement within the limits of the COR.
>
>
> I agree, but why? here a Peter Jones can say: not at all, to have something
> "observable", you need consciousness, and to have consciousness you need a
> physical primitive reality.
>
>
>
>
>
> If we accept that the existence of a COR is entailed by assuming CTM, we
> come naturally to the question of what might be "doing the computation".
>
>
> How could that not be answered by the existence of COR, or by arithmetic. We
> know that both the programs and their execution can be proved to exist in
> elementary arithmetic. The problem comes exclusively from the people who say
> that *a priori* the computation are not enough, and that they need to be
> implemented in the primitive physical reality (that they can't define, but
> the point is logically meaningful until step 8).
>
>
>
>
> In terms of the UDA, by the time we get to Step 7, it should be obvious
> that, in principle, we could build a computer from "primitive" physical
> components that would effectively implement the infinite trace of the UD
> (UD*). Furthermore, if such a computer were indeed to be implemented, the
> COR would necessarily exist in its entirety somewhere within the infinite
> redundancy of that trace.
>
>
> It would exist physically, and lead to the same measure problem, forcing the
> physicalist to bring up an hypothesis that the primitive physical universe
> is "small" to avoid the measure problem.
>
>
>
> This realisation alone might well persuade us, on grounds of explanatory
> parsimony and the avoidance of somewhat strained or ad hoc reservations, to
> accept FAPP that UD*->COR. Should we be so persuaded, any putative
> underlying "physical computer" would have already become effectively
> redundant to further explanation.
>
>
> Yes. At step seven, we can already use Occam, and abandon physicalism. At
> step 8, the move can still be done logically, but it is shown to be a
> god-of-the-gap move.
>
>
>
>
> Notwithstanding this, we may still feel the need to retain reservations of
> practicability. Perhaps the physical universe isn't actually sufficiently
> "robust" to permit the building of such a computer?
>
>
> To build it is not a problem, (I did it), but to run it for a sufficiently
> long time so that we have a measure problem is different.
>
>
>
> Or, even if that were granted, could it not just be the case that no such
> computer actually exists?
>
>
> Well, it exists like prime numbers exists. Same for his execution. Now, I
> doubt that in a physical universe we can run it *forever*.
>
>
>
> Reservations of this sort can indeed be articulated, although worryingly,
> they may still seem to leave us rather vulnerable to being "captured" by
> Bostrom-type simulation scenarios.
>
>
> This assume also the existence of computers, and physical computers.
>
>
>
>
>
> The bottom line however seems to be this: Under CTM, can we justify the
> "singularisation", or confinement, of a computation, and hence whatever is
> deemed to be observable in terms of that computation, to some particular
> physical computer (e.g. a brain)? More generally, can we limit all
> possibility of observation to a particular class of computations wholly
> delimited by the activity of a corresponding sub-class of physical objects
> (uniquely characterisable as "physical computers") within the limits of a
> definitively "physical" universe?
>
>
> That problem appears once we agree that a non physical computation can be as
> conscious as us, and that problems appears at step seven, including its
> solutions. It is because we will take all computations (going through our
> mental states) into account that we have a measure problem, which is the
> stabilization of physical laws problem. Of course after that we need to
> formulate and solve that problem mathematically, and that is what is done in
> AUDA.
>
>
>
>
> This is where Step 8 comes in. Step 7 seeks to destabilise our naive
> intuition about an exclusive 1-to-1 relationship between computations and
> particular physical objects by pointing to the consequences of a physical
> implementation of UD*. Step 8 however is a change of tactic. First, it
> postulates a scenario where physical tokens have been contrived to represent
> a "conscious computation" (either in terms of a brain or in terms of a
> substitute "computer"). Then it sets out to shows how all putatively
> "computational" relations between such tokens could in principle be
> disrupted without change in the net physical action or environmental
> relations of the system that embodies them. Step 8 differs from Step 7 in
> that it seeks in the first instance to undermine the very notion that
> physical activity can robustly embody
>
>
> I agree up to here.
>
>
>
> *any* second-order relations above and beyond those of net physical action.
>
>
>
> Here I disagree. I would say instead "Step 8 differs from Step 7 in that it
> seeks in the first instance to undermine the very notion that physical
> activity can robustly embody consciousness or the first person
> subjectivity". I don't see why it would undermine the second or higher order
> relation. The problem is only for the higher order *first person* relation
> with the physical activity of the device, ISTM (It seems to me).
>
>
>
>
>
> Accepting such a stringent conclusion would then seem to rule out CTM prima
> facie. The only possibility of salvaging it would lie in an explanatory
> strategy in terms of which computational relations take logical precedence
> over physical ones.
>
>
> But this somehow, we already know. "Computation" is prima facie a notion of
> pure arithmetic. the difficulty is already in the phsyicist hands, to
> explain how it implements a computation in physics, but that is not to hard,
> as the physical lwas, and many different subparts are Turing universal. What
> they cannot solve (and ignore) is that they lost the usual 1p-3p link. Here,
> what saves us, is incompleteness which will explains that the 1-self is not
> isomorphic to the 3p-self, and lives in some different semantical space,
> incompatible with a primitive physics.
>
>
>
> Given that computational relations are effectively arithmetical, this in
> turn leads to the conclusion that CTM->UD*->COR (or more generally, that
> each implies the others).
>
> Notwithstanding this it would seem that Step 8 is not wholly persuasive to
> everybody, so is there yet another tack? The line of argument that I've been
> pursuing with Brent has led me to consider the following analogy, which I'm
> sure you'll recognise. Consider something like an LCD screen as constituting
> the "universe of all possible movie-dramas". In terms of this analogy, what
> are the referents of any "physical observations" on the part of the dramatis
> personae featured in such presentations? IOW what are we to suppose Joe
> Friday to be referring to when he asks for "Just the facts, ma'am"? Well,
> the one thing we can be sure of is that NO such reference can allude to the
> "underlying physics" (i.e. the pixels and their relations) of the LCD
> display. If this analogy holds, at least in general outline, what
> justification, under CTM, could remain for any assumption that our own
> observations and references might "accidentally" allude to some
> "LCD-physics" postulated, mutatis mutandis, as underlying the COR? Would it
> not seem extraordinary that any such underlying physics could contrive to
> "refer to itself" through the medium of its merely computational
> derivatives?
>
>
> Not sure. If arithmetic can do that, why not physics? Well, because the MGA
> explains you need to put infinite magic to singularize consciousness, and
> still surivive the comp substitution qua computatio (and not the will of a
> God-of-the-gap).
>
>
>
> This last point might seem determinative, but might there not still be a
> last-ditch redemption, of a physics underlying computation, in terms of
> "evolution"? IOW, might it not be argued that the acquisition of internal
> "computational" models of their physical environment confers a survival
> advantage on the physical creatures that embody them? But any such argument
> would, of course, be completely circular; assuming CTM, it begins and ends
> in the COR. IOW, arguing in this way would be to ignore the fact that the
> history of such creatures, their survival, and the environment in which this
> is supposed to take place, all lie within the COR, not the putative regime
> of any "underlying physics". THAT "physics" would necessarily be entirely
> inscrutable and inaccessible for reference at the level of the COR (think of
> the LCD analogy). And hence we simply would have no a priori justification
> for assuming the observational physics of the COR to be isomorphic with some
> notional underlying "LCD-physics". In fact, once having assumed CTM, we
> would have no further basis for assigning THAT physics any role whatsoever
> in our explanatory strategy.
>
>
> At first sight I agree here.
>
> Bruno
>
>
>
> David
>
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> http://iridia.ulb.ac.be/~marchal/
>
>
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