On 10/05/2017 12:41 am, Bruno Marchal wrote:
On 09 May 2017, at 09:36, Bruce Kellett wrote:
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.
The sequence of computational steps may be deterministic, but the net
result in the infinite UD is random. Think of Boltzmann's case, a gas of
a very large number of molecules. The molecules move and interact
according to entirely deterministic laws, but ergodic theory indicates
that after a suitable time, the motions of the molecules will be
effectively random. I think the same must happen with the dovetailer:
although each program is deterministic, the dovetailing of infinitely
many such programs means that sequences of individual steps are random
(or indistinguishable from random).
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.
I was deliberately vague in specifying what was meant by a "conscious
moment". I doubt that it is of zero duration, but the duration is
indeterminate. Beside, there is no concept of time in the UD, so it is
hard to say what a conscious moment might actually be -- some sequence
of computational steps, perhaps -- but how many? A time capsule is
certainly self-contained. Whether these overlap or not to give a sense
of continuity is another question, and would seem merely to extend the
notion of a conscious moment in time somewhat -- but what is time?
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.
The computations underlying the conscious moment have, then, to also
compute the physics that renders the memories veridicial -- but that
involves memories stretching back tens of years. An awful lot of
computations have to come together to make consciousness that means
anything. Making the probability in the sea of random noise smaller and
smaller all the time.
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.
Which probably involves the whole universe, from the big bang to the
eventual heat death -- else memories are not veridical.
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.
Not really at this stage -- just an alternative understanding of the
dovetailer.
Bruce
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
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