On 09 May 2017, at 09:36, Bruce Kellett wrote:
On 9/05/2017 4:36 pm, David Nyman wrote:
On 9 May 2017 6:16 a.m., "Bruce Kellett"
<[email protected]> wrote:
On 9/05/2017 1:57 am, David Nyman wrote:
On 8 May 2017 8:21 a.m., "Bruce Kellett"
<[email protected]> wrote:
On 8/05/2017 4:53 pm, David Nyman wrote:
Both Hoyle's pigeon holes and Barbour's time capsules assume that
there is a coherent underlying physics with regular exceptionless
laws. Until you have something like that, you cannot define
consistent continuations.
But I'm afraid that's implied by assumption unless one takes the
view that the evolution of physical states is fundamentally
incomputable,
But I thought that that was what Bruno claimed. If one assumes
physics in one's derivation, then the circularity is vicious.
Oh dear no, that's not right at all. What is uncomputable is any
extrinsically conceived *extraction* of physics from the
computational Babel consequent on the theory. There is no possible
search function for this. That extraction then is necessarily a
complex consequence of observer selection. Post
such extraction, the evolution of
physical states is then by assumption finitely computable, modulo
the FPI, else computationalism must fail as a theory of mind or of
physics. At this point the objective situation, mutatis mutandis,
is essentially equivalent to Everett's relative state assumptions.
The other point on which I must take you to task is again the
question of circularity. It's not the job of computationalism's
toy model to explicate every detail of the extraction of physics,
although it's already the case that it *predicts* the multiple
continuations implicit in the wavefunction, which is more than can
be said for QM itself which merely retrodicts them (again modulo
the FPI). Given the conjunction of the assumption of
computationalism and our observation of the physical environment
described by QM, all the theory has to show at this stage is that
it is not incompatible with these data (as it would be if, say,
the evolution of the wavefunction itself were shown to be
uncomputable). It should further explicate some reasonably
convincing justification for why just such a physics might be
expected to underpin the effective environment we observe. But the
*facts* of our observation of such a physics are not at issue.
There is no relevant question of circularity to deal with here.
As to the so called Occam catastrophe, as exemplified in your
Boltzmann brain scenario, potential resolution necessarily can be
understood under computationalism only from a first person
perspective, as I previously suggested to you. We need to justify,
in terms of a subjective measure, why we should indeed expect the
physics we observe to emerge as the predominating computational
mechanism underlying our normally intelligible perceptions. To do
this we only need to show that "last Tuesday" computational
snippets can only reinforce, and magical or unintelligible ones
cannot interfere, with "normally intelligible" and complexly
connected continuations. A way to grasp this intuitively is in
terms of something like Hoyle's "amnesic multiple personality"
heuristic which, though as you say it was originally based on the
assumption of physics, IMO illustrates the relevant considerations
equally intuitively on computational assumptions. In any case, the
analogy of a multitasking OS that I also mentioned suffices
equally well in this regard.
From this perspective, no amount of white noise in continuations
of "Boltzmann" computations could make a substantive subjective
difference. The reason being that the consequence is
overwhelmingly likely to be a total subjective unintelligibility
which will plausibly tend to be utterly swamped, in the struggle
of forgetting and remembering, by "normally intelligible"
continuations. The FPI is, obviously, the relevant consideration
in this regard. This is what I meant when I said that an absence
of evidence for this sort of pathology or unintelligibility is not
evidence of its absence. It suffices that these out of phase
components of experience be swamped in the battle for what one
might term personal subjective emergence. They just typically get
forgotten far more frequently than they get remembered by Hoyle's
multiply solipsistic agent. Hence what we may think of as
pathological scenarios would be expected to be very poor and
haphazard candidates in the ongoing struggle for apparently
persistent, pervasive and lawful subjective emergence. What would
emerge with these characteristics would then be consistently
remembered histories underpinned by a robust and reiterative
physical mechanism whose highly selective observation by us would
then be the final evidence of its predomination in this epic
personal struggle.
I gave you an illustration a few days ago (on which you didn't
comment) of what one might term the "psycho-theological" aspect of
computationalism. I said that consciousness or first person
subjectivity was really a pointless cherry on the cake of physics
whose mechanism must be assumed to proceed without any a priori
need of such a baroque supernumerary assumption. Indeed it can
only be an a posteriori datum tacked on to the physical scheme of
things. Computationalism, by contrast, can only be understood in
the final analysis as a synthesis of all possible subjective
personal histories. "Point of view" is then just what prevents
them from all happening at once. Thus physics, under the same
assumptions, can in turn be understood finally as the successful
computational generator underlying the "dreams of the machines".
David
I find most of what you say here very much a matter of wishful
thinking, and not entirely consistent at that. Let me come at it in
a different way.
I find Barbour's idea of time capsules quite helpful here. Each
time capsule is a self-contained conscious moment. There is no
progression necessarily involved, so the computation that gives one
conscious moment is complete in itself, and independent of other
such conscious moments. (In Barbour's picture, these moments are
points in configuration space that are related physically, but we
do not use that aspect here.) In the moment, you are self-aware,
and aware of memories that give you a concept of self. But in that
moment there is no way that you can know whether these memories are
veridicial or not -- they could well all be completely false, in
which case there is no "you" that continues through time as a
related series of experiences. Each experienced moment is complete
in itself, and there is no continuation. If all you have is the
moment of consciousness, you can go no further than this. It is all
an illusion, and there is no physics to extract.
Of course, this is a solipsistic conclusion, but there is nothing
in our experience of consciousness that shows solipsism to be
false. The "I" is the "I" of the moment, nothing more.
Now consider the UD in arithmetic. It dovetails all possible
programs -- does all possible computations -- but most computations
have nothing to do with consciousness. If we use Boltzmann's
thermodynamics as an illustration of the situation, the
computations of the dovetailer represent a state of thermal
equilibrium, a state of maximum entropy. The characteristic of
thermal equilibrium is that every microstate is equally likely -- a
state of complete chaos. Similarly, in the dovetailer, every
computation is equally likely and there is no order whatsoever.
Occasionally, in Boltzmann's thermal equilibrium there are
fluctuations to states of lower entropy in which some order
emerges, but according to the second law of thermodynamics, these
always return to equilibrium. Similarly, in the computations of the
dovetailer, there are occasionally computations that make some sort
of internal sense. Some of these correspond to conscious moments.
But, as in the thermal case, these rapidly return to meaningless
noise. Small fluctuations to momentary order are overwhelmingly
more likely than larger fluctuations to order that persists over
time -- or computations that correspond to an extended sequence of
(consistent) conscious states. In fact, within the dovetailer there
are undoubtedly sequences of computations that correspond to the
entire history of the observable universe, from the big bang
through to the final heat death. But such calculations are of
measure zero in the overall picture.
So, if one is to take the statistics of computations that pass
through one's instantaneous conscious state in order to extract
meaningful physics, one will find that the overwhelming majority of
these computations are of short-lived conscious moments that
rapidly return to meaningless chaos, nothing more. The dovetailer
would then say that no consistent physics can ever be extracted
from the statistics over conscious moments, because these
statistics are dominated by chaotic continuations.
That does not necessarily mean that no consistent physics exists --
as I said, all of physics will be in the computations of the
dovetailer somewhere. All it means is that such physics cannot be
extracted by considering individual conscious moments as primary.
Physics has to have an independent existence, or it has no
existence at all, and solipsism is the only answer.
Thanks for your interesting comments Bruce. It's difficult to know
how to respond because I still feel we are somehow at cross
purposes. Perhaps I should start by commenting on the matter of
wishful thinking. As I said to Brent, I don't see myself as an
apologist for computationalism. Rather I'm trying to understand its
possible implications. My views on the matter have changed over the
years, particularly as a result of discussion on this forum, and I
am perhaps more persuaded than I was originally (which is to say
not at all). But I don't believe my wishes are really part of the
picture. It's rather that I deliberately allow myself a modicum of
intuitive latitude in these discussions - one might say going just
a bit further than confidence in my position would allow in less
speculative topics - mainly in order to stimulate the broadest
possible critique from a valuable community of varied expertise.
The thing that changed my view the most, in direct contrast to what
you say above, was considering the matter from a first personal
perspective rather than the traditional "view from nowhere". By
this I don't mean that I believe consciousness to be more
"fundamental" than physics, but rather that I began to see Bruno's
point that physics would have to be a subjectively driven
filtration from the computational Babel if computationalism as a
whole were to make any sense. The alphabetical Babel is a useless
chaos because of the impossibility of an extrinsic search function
but the possibility of intrinsic self-selection via
subjectivity seems like a more promising proposition. But of course
this demands a fundamental theory of subjectivity and it is indeed
a fresh approach to this vexing question that Bruno has brought to
the party. I suspect the amount and occasional ferocity of focus on
his approach stems from something more than the mere desire to
prove him wrong.
All that said, the point where I feel we're talking past each other
is precisely on the issue of the extraction of physics. As I tried
to point out, the facts of the matter are not what is at issue
here. Rather the question hinges on whether it is reasonable to
suppose, against the assumed background of UD*, that the vast
majority of conscious moments would be a consequence of their
supervening computationally on the observed physical environment
rather than on random fluctuations. And the reason I make use of
Hoyle's or Barbour's analogies is that they seem to lead naturally
to a form of solipsism that I've called the amnesic multiple
personality. Hoyle himself points this out. And far from seeing
this as terminal for the argument (although frankly it amuses me
that this despised philosophical position might be thus
rehabilitated) I find it genuinely enlightening on the question
of how to reconcile probability in a quasi-frequentist framework in
an overall context in which "everything happens" with certainty.
This is where what I've called the struggle or battle between
remembering and forgetting comes to the fore. Admittedly it's an
unfamiliar idea and hardly easy to come to terms with, not least
for me, but in struggling with it I've found it genuinely
enlightening with respect to many otherwise intractable puzzles,
not least to do with personal identity and its putative history. In
terms of our discussion, the area of disagreement which most
puzzles me is why you take the view that the experience of a unique
agent such as the one analogised by Hoyle or Barbour would be
dominated by random events rather than the order imposed by the
predominance of a robust physical-computational mechanism. I don't
see why a mechanism "singularised" or selected in this manner would
*at that point* fail to possess the necessary "independence" in the
sense you demand of it. After all, this seems little different in
effect from the so called anthropic selection invoked in other
frameworks. I'm probably being a bit slow here, but could you
explain again why you take this view, preferably putting it in the
context of the approach I describe above if at all possible. As I
said to Brent, a counter-argument is more enlightening than one
that is merely different.
Yes, it does seem that we are each outlining positions and arguments
that do not necessarily intersect at many points. I will try and
answer some of your more direct questions. Why do I take the view
that "the experience of a unique agent such as the one analogised by
Hoyle or Barbour would be dominated by random events rather than the
order imposed by the predominance of a robust physical-computational
mechanism." The reason is that I am starting from a slightly
different perspective -- I am looking at the UD as a system in its
own right. The questions seem to concern statistics extracted from
the behaviour of this system. When approaching such a question, I
tend to look on the thermodynamic, or statistical mechanical
properties of such a random system. If you take the UD, with its
completely random operation over all possible (computer) programs,
the analogy that comes to mind is that of thermal equilibrium --
every possible state has equal probability of occurring. Ergodic
theory is possible also relevant, but I have less familiarity with
that, so tend to stick to ideas deriving from Boltzmann. Given this
state of thermal equilibrium, states of some order -- such as
conscious moments -- are going to be unlikely, and fluctuations that
give single conscious moments are overwhelmingly more likely than
more extended fluctuations that give a sequence of related conscious
moments.
Not sure I understand. The UD is not random at all. What is random is
the First Person Indeterminacy on all the stable continuations of my
states, as seen by the first person, so the first thing to do is to
get a mathematical theory of the first person (which I take to
Theaetetus, as Gödel's incompleteness makes it work again, again
Socrates opinion).
Given also the insight from Barbour that each conscious moment --
time capsule -- is self contained,
I am not sure that such an intuition is correct. A conscious moment
needs at least two universal numbers, but in fine relies on an
infinity of them. Nor do I conceive such a thing as an observer
moment. the semantic of all first person view (the modalities with "&
p" attached to them) are topological. Consciousness is always on an
interval, not on a discrete point in some time frame.
and in itself, a complete explanation of our conscious experience,
the computations that pass through our conscious moments are
overwhelmingly likely to be random, with just small fluctuations
from equilibrium. I.e., single conscious moments with no consistent
continuation-- going from white noise to white noise. This is, of
course, Russell's Occam catastrophe in a different guise. The
experience of the agent is not random -- they experience conscious
moments with a seemingly coherent chain of memories giving a
comprehensible history -- but there is no reason to suppose that
these memories are veridical.
They will be more or less plausible, with respect to the normal
computations, if they exist of course, but they have to exist if
computationalism is correct.
So there is no order imposed by the computational mechanism.
All computation are ordered structure, ordered by the universal
numbers which implement them. But indeed, the first person duration is
not directly ordered by this or that universal numbers, but by all
those who operate the computations which exists below my substitution
level.
The statistics over these conscious moments does not give rise to
any consistent physics. I say that "physics has to have an
independent existence" because the failure of the attempt to extract
physics from the UD means that the only way one can connect these
independent 'conscious moments' is if they are, following Barbour,
points in an independently existing configurations space. Barbour
calls this "Platonia", within which physics is defined, but this is
far from the platonia of arithmetical realism. The upshot is that
physics does not come from the UD, but from somewhere else -- that
elsewhere not necessarily clearly specified at this point.
Since the reversal, or the extraction of physics, seems to me to be
the weak point of Bruno's argument,
Well, the goal of the UDA is just to transform the mind-body problem
into a body problem in arithmetic.
Then what is weak in the AUDA, the math part, is that nobody seems to
be interested in solving the open problems, but that is contingent. I
am not sure you can say that it is weak. It is only unfinished, but
the complexity comes from the difficulty of the subject, which is
naturally reflected in the open problems? To find quantum logic where
it is needed is on the contrary a good sign that we might extract the
full measure, then works à-la-Hardy or Russell's, can be used to
progress.
it is right that we should spend more time looking at alternative
interpretations of the UDA.
UDA is a argument, as such it does not admit any interpretation. It is
valid, or non valid. I guess you mean to search an alternative to
mechanism.
This, I would understand if the material hypostases would have
collapsed into classical logic, or would be strongly opposed to
quantum logic, but without evidence for non mechanism, I am not sure
if it is not premature to abandon mechanism , given that mechanism
already give a quantum logic. To abandon computationalism at this
stage, before testing the logic of the observable that we already
have, seems weird to me.
Bruno
Bruce
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