Re: Bayes Destroyed?

From: Bruno Marchal <>
Date: Mon, 31 Aug 2009 10:10:19 +0200

On 31 Aug 2009, at 03:50, marc.geddes wrote:

> On Aug 31, 4:19 am, Bruno Marchal <> wrote:
>> On 30 Aug 2009, at 10:12, marc.geddes wrote:
>> But look at this. I decide to do the following experience. I prepare
>> an electron so that it is in state up+down. I measure it in the base
>> {up, down}, and I decide to take holiday in the North if I find it
>> up,
>> and to the south, if I find it down.
>> Not only that. I decide to go, after the holiday, to the amnesia
>> center where all my memories, from the state of the electron to
>> everything which follows, except my feeling about how much I enjoy
>> the
>> holliday. And I am asked to answer by yes or no to the question "did
>> you enjoy your holiday. Then, thanks to the amnesia my yes+no states
>> will be used In this way. I interfere with myself, and what will
>> follow in the new branch where I have fuse with myself, my, and your,
>> future is determined by my contentment qualia, in the two branches of
>> the waves.
> This assumes that qualia are completely determined by the wave
> function, which (since Bohm is non-reductionist) I'm sure he'd
> dispute. The wave function only predicts physical states, it does not
> neccesserily completely determine higher-level properties such qualia
> (although of course qualia depends on low-level physics). If the wave
> function DID completely determine the qualia, your example would
> indeed contradict Bohm - but Bohm already admits he's non-
> reductionist.

Well, meaning that he is non computationalist. No problem, in free

> A weakness of MWI is that it does not describe the reality we actually
> see - additional steps are needed to convert wave function to human
> observables - Bohm makes this clear, MWI just disguises it. Even in
> MWI, additional unexpected steps (Born probabilities derivation etc)
> are needed to convert wave function to what we actually observe.

I am not sure. Bohm has to use an unknwown and unspecified (but very
vaguely) theory of mind.
The MWI has to use only comp (a modern version of a very old theory of
(Then I point on the fact that if we take comp seriously the SWE has
to be justified from numbers only, but that is nice because it points
to a further simplification of the theory).

> But MWI has the same problem, it just states it in different terms, in
> MWI all worlds exist, but which one will we actually observe? In
> Bohm, only one world is there, but which of the paths in the wave
> function is it?

Not at all. The question "which world" is reduced to the question "why
W" or "Why M" in an WM self-duplication experiment, or to the child
question "why do I feel to be me and not my brother". Comp justifies
why universal machine have to ask such question, and why they cannot
answer them, and why they can explain that such question have no
answer when assuming comp.
Bohm has to make special an observable (position), to threat away
locality, to introduce hidden variables, and a supplementary equation,
which describe necessarily hidden things.


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Received on Mon Aug 31 2009 - 10:10:19 PDT

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