On 3/18/2012 10:25 AM, John Clark wrote:
On Sat, Mar 17, 2012  Bruno Marchal <marc...@ulb.ac.be 
<mailto:marc...@ulb.ac.be>> wrote:

        >>  we can conclude that the Helsinki man will feel he has survived in 
        cities because HE HAS BEEN DUPLICATED and is now *in both cities*.

    > But he feels he is in only one city.


    > He used your trick to predict that he will be in Moscow with 100%, but he 
woke in


    > Ah! But you say he know that he has been duplicated and that he is in 
    AND in Moscow. But how could he *know* that?

If the Helsinki man didn't know he (pronoun use OK here) was going to be duplicated then it can hardly be expected that the Helsinki man is going to be able to give probabilities based on that fact.

A silly, evasive reply. People estimate probabilities of outcomes all the time *conditional* on some event: If I fly to Washington for the week, what's the probability I will need an umbrella?

    > He can only *verifie* that. The presence, or not, or the other, the 
    is like a scientific needing some confirmation. He can give a call to 
Moscow, to say
    hello to "himself", but bad luck, he just learned that the reconstitution 
    failed in Moscow. This illustrates that each copies can know where they 
are, but can
    only believe the other copy is or not in the other city.

It does not matter to the Helsinki man in Helsinki if the Helsinki man in Moscow (the Moscow man for short) or the Helsinki man in Washington (the Washington man for short) believe in the existence of each other or not, because by direct observation the Helsinki man knows he is in Moscow and by direct observation the Helsinki man knows he is in Washington. How can the Helsinki man be at 2 places at once? BECAUSE HE HAS BEEN DUPLICATED. But they now hold different views on where they are, what are the consequences of that? The Helsinki man differentiates into two, the Moscow man and the Washington man; although both are still the Helsinki man, at least in the same way that although you Bruno Marchal have changed from what you were yesterday, you Bruno Marchal of today are still the man you were yesterday. And the point in space your body was in yesterday or today is not relevant to the question at hand.

    > you confuse an intellectual hybrid of your 1-you with the set {3-you in 
M, 3-you
    in W},

The only thing this homemade gobbledegook achieves is confusion, mostly to 

    > By definition of first person (content or sequence of content of the 

Then I (the original John K Clark or the copy, there is no way for me to tell the difference) share the same "first person" (whatever the hell that is) with the person who just materialized in front of me in the duplicating chamber, because the diary I'm holding looks just like the one that other fellow is holding, and I can vividly remember writing every single line of that diary and he says he remembers doing that exact same thing too.

What you share is a history and memories thereof. As soon as those diverge due to either internal or external effects then there will be two distinct people JC-1 and JC-2.

    > You seem to continue to oscillate between there is no 1-indeterminacy, 
because ...
    100% for Moscow, and there is an indeterminacy (but it is trivial, nothing 

There is rock stability and no oscillation whatsoever; Indeterminacy is always with us, in the real world thanks to deterministic chaos, in physics thanks to Heisenberg and even in pure mathematics thanks to Godel and Turing, but your complications do not add any more because no matter how convoluted you make them as long as you make clear who "I" and "you" and "he" is your additional probabilities always boil down to 0% or 100%. And if you don't make it clear then everything is meaningless.

I agree with your criticism of Bruno's use of pronouns, but I don't think it's essential to his argument.

Here's a free neutron, n. What is the probability that you will observe it to decay in the next 10min? This is a very standard form of question about probability and the answer is 1/2. Bruno (and Everett) want to replace it with, "Ten minutes from now there will be two JCs one of which has observed the decay of n and one of which has not and they have equal measure in the Hilbert space of the universe." You don't need any pronouns to express it.


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