On 06/03/11 18:47, Bruno Marchal wrote:
On 06 Mar 2011, at 14:16, Andrew Soltau wrote:
On 05/03/11 14:46, Bruno Marchal wrote:
Chalmers told me that first person indeterminacy does not exist, and
not much more, and Bitbol never reply to me when I sent him my PhD.
I am still not sure if I correctly understand your concept of first
person indeterminacy, though I have gone over your paper The first
person computationalist indeterminacy many times. Your opening
paragraph states "The notion of first person, or subjective,
computationalist indeterminacy is a notion which makes possible to
explain how, in a context of purely third person (objective)
determinacy, experiments can be designed exhibiting, from the points
of view of the subjects involved, a necessary lack of apparent
determinate outcome", but for all known experiments and experiential
reporting, there is always a determinate outcome.
?
You state that "The notion of first person ... indeterminacy is a notion
which makes possible to explain how, in a context of purely third person
(objective) determinacy, experiments can be designed exhibiting, from
the points of view of the subjects involved, a necessary lack of
apparent determinate outcome"
Why are we examining " a lack of apparent determinate outcome" when, for
all known experiments and experiential reporting, there is always a
determinate outcome?
If you prepare an electron in the state (up + down), and decide to
look at it with a {up, down} measuring apparatus, you will experience
the personal outcome as non determinate.
This is what I don't understand. When I look at it with a {up, down}
measuring apparatus, I must necessarily experience a specific
determinate outcome, reported by the {up, down} measuring apparatus. The
whole puzzle of the measurement problem is that I always experience a
specific determinate outcome, reported by the {up, down} measuring
apparatus, despite the fact that objectively both results must obtain.
You can say with Everett that the outcome of the whole process
describing you+electron is determinate: it is you-electron-up +
you-electron-down, but with or without collapse, the outcome you are
experiencing is not determinate. That is the quantum indeterminacy.
There is only quantum indeterminacy in the absence of collapse. I can
only make sense of your statement "but with or without collapse, the
outcome you are experiencing is not determinate." if you mean "you" to
be the ensemble of all possible mes. Following Everett, for the physical
observer the outcome is not determinate, but the whole point is that the
*experience* is determinate. Hence the measurement problem.
With comp, it is simpler. It is the fact that if you are a machine,
then I can scan you, annihilate you and reconstitute you in two
different place (W and M, say). If I ask you what will happen, you can
still say that the outcome is determinate, when seen in the third
person view (I will be both in W and in M), but if you are asked what
will be your personal experience (what you will put in your memory or
diary), you might understand that such a personal outcome cannot be
determined. You cannot say "I will be certainly in W", because you
can understand the one who will be in M will have to say "I was
wrong", and comp makes his opinion valuable. You cannot say "I will be
in W and in M", because you know that you will not write "Oh, I see I
am in both cities at once", etc...
OK
Basically, Everett makes the quantum indeterminacy a sort of
particular case of comp indeterminacy, except that I agree with
Deutsch that the quantum indterminacy does not involve physical
splitting. Only consciousness differentiates. Eventually that is what
happens with comp too.
OK
I imagine I am simply misunderstanding the language. Do you mean
simply the apparent lack of determincy of Wigner's friend's
experience of the experiment in Wigner's point of view? My confusion
comes from the fact that from Wigner's friend's point of view, the
point of view of the subject involved, the outcome is always
determinate.
I was trying to establish the exact meaning of the phrase first
person indeterminacy in an earlier conversation. I stated
By 'first person indeterminacy' in 1 below, I am reading this as the
indeterminacy regarding the actual location and thus physical context
/ instantiation of this observer.
It concerns the future of personal experience, in the experiments of
comp (or quantum) self-duplication.
You can also consider the iteration of self-duplication. If you
iterate 64 times, there will be 2^64 versions of you. First person
indeterminacy is the fact that most of the 2^64 versions of you will
agree that they were unable to predict in advance what was the next
outcome at each iteration. Most will consider that their histories (like:
"WMMMWWMWMMMMWWWMMWMMWWWWWM ..." (length 64)
are random, even Chaitin-incompressible.
Does this help?
So, 'first person indeterminacy' simply means that I don't know what
observation I will make next?
but your answer simply stated that I was making 'treachery to invoke
the physical', and gave me no answer on the meaning of the phrase I
was trying to clarify!
You can use the physical for illustrating a point, but you cannot use
the *primary physical* as a starting assumption, unless you make a
reductio ad absurdum.
If you have a trouble with the first person indeterminacy notion, it
is normal you have a trouble with the reversal, which is a
consequence of it.
I guess I'm not there yet, as I don't see a connection between not
knowing what observation I will make next and the reversal you refer to.
I look forward to understanding both!
Bruno
http://iridia.ulb.ac.be/~marchal/
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