On 03 Mar 2012, at 01:56, Joseph Knight wrote:

On Fri, Mar 2, 2012 at 3:03 AM, Bruno Marchal <marc...@ulb.ac.be> wrote: Let me ask a question to everybody. Consider the WM duplication, starting from Helsinki, but this time, in W, you are reconstituted in two exemplars, in exactly the same environment. Is the probability, asked in Helsinki, to find yourself in W equal to 2/3 or to 1/2. My current answer, not yet verified with the logics, is that if the two computations in W are exactly identical forever, then it is 1/2, but if they diverge soon or later, then the probability is [2/3].

Why is that?

But I am not sure of this. What do you think?

My intuition is that the probability should be 2/3 in either case.

Thanks for answering. I will comment asap (busy week-end!). But so I let also the others to think on the matter before I explain. The question is more subtle than it looks. I don't have the answer in local situations, but in front of the UD, it might be a little more simple, but still hard.

I can give you another problem, equivalent to a question found by Bostrom, which can give an hint:

Suppose you are again read and cut in Helsinki, and reconstituted in Moscow and Washington, but now you are told in advance that in W you will have an artificial brain made of big wires, and in W the artificial brain will use thin wires. The level is correct, by assumption. Also, the thin wires are solid and works perfectly from a 3p pov. What is the probability that you will find yourself in W?

Another way to handle this question is just to count the 1p experiences, but this will not work (this leads to white noises, do you see why?), so we have to separate the different 3-computations, like you did, but not as much as leading to an absurdity in the situation described by Bostrom (although he seems to defend it ...)


PS I have to go, and I might be unable to comment before Monday afternoon. I will comment Craig and Stephen asap, which means later, sorry.


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