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. You say that
this then runs all possible computations and, indeed, runs any finite
computation indefinitely often. Let us accept this for the moment. Then
there is a computation that instantiates the entire observable universe,
from the big bang to indefinitely far into the future. 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.
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.
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.
In this situation, physics is to be done in the usual way --
observation, experimentation and the development of corrigible theories.
"Questioning the machine" will never go anywhere because finite
continuations of local conscious calculations are not sufficiently
coherent. It is only within the larger computation that any consistent
physics can emerge.
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.
You have difficulty extracting physics from your theory because you are
looking in the wrong place.
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. 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.
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?
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
