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.

?

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. 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.

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...

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.


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?


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.

Bruno


http://iridia.ulb.ac.be/~marchal/



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