On 6/29/2015 5:41 AM, Bruno Marchal wrote:
On 29 Jun 2015, at 12:27, Bruce Kellett wrote:
Bruno Marchal wrote:
On 29 Jun 2015, at 01:37, Bruce Kellett wrote:
Bruno Marchal wrote:
On 26 Jun 2015, at 04:19, Bruce Kellett wrote:
Bruno Marchal wrote:
On 25 Jun 2015, at 14:27, Bruce Kellett wrote:
My contention is that the body (and the rest of the world) is essential for a
satisfactory account of personal identity.
I can understand, but that remains possibly true phenomenologically. Unless you
explain me why you use your theory to refuse a brain transplant to a kids who will
die without?
A brain transplant means replacing one physic brain with another physical brain. I
think you need to explain why we need a transplant -- why not just replace the
brain with the appropriate universal number tattooed on the forehead?
because in that case (admitting some sense in it) would not save your relative
manisfestation locally.
Personal identity is not just a matter of memories.
Right, and that is clear from the AUDA definition. But for UDA, personal memory is
enough to get the reversal.
You have not *derived* any reversal at any stage -- you have only ever asserted or
assumed it.
The reversal follows logically from COMP + ROBUST-UNIVERSE at step seven. If not, ask
me what you don't understand.
The trouble is that there is a simpler and more believable interpretation of the UD
available. Let us go to a robust universe or, more particularly, the UD as run in
Platonia or arithmetic.
At step seven, we use the concreteness of the UD. But let us see.
You say that this then runs all possible computations and, indeed, runs any finite
computation indefinitely often.
It runs also the infinite computations infinitely often. OK.
Let us accept this for the moment.
This is provable. But OK.
Then there is a computation that instantiates the entire observable universe, from the
big bang to indefinitely far into the future.
Not necessarily. The observable is eventually given by the limit on all non stopping
computations, and that limit might be computable, or not. We don't know what is the case.
If the UD runs all "infinite computations and infinitely often" then in what sense can it
fail to compute the limit?
I do agree, yet, that all computations approximating the physical universe are run by
the UD.
This then gives the entire universe. The computation may be repeated many times, but
by the identity of indiscernibles, those repetitions are just the same universe.
Assuming that the limit above is computable, which can hardly be the case (unless my
generalized brain is the entire universe, which I doubt, but of course, we don't know,
although the QM/MWI suggests empirically that it is not the case).
There will be computations that differ from the one giving this universe to greater or
lesser degrees, so these give neighbouring universes that differ in these degrees.
Actually, this is just the level 1 multiverse of Tegmark. Given eternal inflation,
there are an infinite number of O-regions (observable universes) sharing our basic
physics. The idea is that there are only a finite number of possible histories for
these O-regions, so any history is repeated indefinitely often. And for any history,
all close and not-so-close copies are also frequently repeated. This is just what comes
out of the UD as well as these physical theories.
More or less OK.
Computations also exist that correspond to less than complete universes, or give
inconsistent physics, or whatever. The very limited computation that gives an
individual consciousness or conscious moment is insignificant in the bulk, and because
of the problem of consistent continuations, those "moments" have zero measure. So we do
not have the situation of "reversal", where the physics is derived from the
continuations of these moments. The physics is given by the extended computations that
create entire observable universe.
But if the physical universe run the UD, to predict (conceptually) if this apple will
fall on the ground, I must look at all computation going through my current state (where
I look at the apple still in my hands). How would you do? That is obligatory by the
(even just local) FPI.
In this situation, physics is to be done in the usual way -- observation,
experimentation and the development of corrigible theories.
Nobdiy will ever arguye that experiemental physics should be done in other ways.
Theoretical physics and fundamental physics will change but just by elimination of
redundant hypotheses, and by the abandon of primary matter (sometimes already abandoned
by physicists themselves).
"Questioning the machine" will never go anywhere because finite continuations of local
conscious calculations are not sufficiently coherent.
On which view? That is true for []p, but false for []p & <>t.
Are you saying that it is true that all provable propositions are not sufficiently
coherent to instantiate a consciousness? But the set of provable propositions with the
added axioms of consistency are?
Are you not suffering of some Dunning-Kruger symptoms? If you have a proof that finite
continuations of local conscious calculations are not sufficiently coherent, then you
could refute comp. Do it, then.
I think Bruce is saying that you don't have a proof that they are sufficiently coherent
and so comp doesn't entail the reversal. His argument is a defeater of a proof, not a
proof of the contrary.
Brent
It is only within the larger computation that any consistent physics can emerge.
The infinitely many one, yes, but this works only if it wins the UD measure, and change
nothing in the fact that physics is determined by the measure on all computations.
This means that physics is completely computable -- Turing emulable. But that is what
quantum mechanics in the Everettian interpretation tells us. Unitary evolution
preserves (quantum) information, and is completely calculable.
Which suggests that the quantum part of QM is part of the winner program for the
measure, but this remains neutral on the hamiltonian.
You have difficulty extracting physics from your theory because you are looking in the
wrong place.
The point is independent of the extraction. The UDA point is that the extraction exists,
and can be find by interviewing the machine.
Then, I don't know to which difficulty you allude too.
On the contrary I am amazed of what is already derived.
Now, I am not claiming that the above outline is correct, or that I even believe it.
But it is a more coherent interpretation of the scenario you paint through the UDA than
the arguments you give.
I have not seen your point. The reversal still occurs at step 7, assuming a primitive
robust universe. If the entire physical universe is computable, you still need to prove
this and justify its winning measure ability to solve the mind-body problem.
Given that there are alternative, more plausible interpretations of the idea that all
computations are present in arithmetic, I do not feel in the least constrained to
accept your particular view.
Nice try, but you made statements without proof (see above), and I don't see where in
your argument you compare the comp predictions and the empirical predictions, except by
your invocation of a "real physical universe", which begs the question and use
implicitly some non Turing emulable ability of matter to select a computation.
Bruno
Bruce
Then in step 8, the assumption "ROBUST-UNIVERSE" is replaced by the usual weak form of
Occam razor, as we can never prove something about reality without invoking it.
Why don't you ask question instead of talking like you find a flaw? If you find a flaw
tell us precisely in which step please. Apparently you still have a problem with step
7, before MGA, as there is a reversal at step seven. Don't you see it? How do you
predict the result of an experience of physics in step 7?
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