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.
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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