cousin_it comments on indexical uncertainty and the Axiom of Independence - Less Wrong

9 Post author: Wei_Dai 07 June 2009 09:18AM

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Comment author: Wei_Dai 05 August 2009 01:38:16AM *  4 points [-]

It seems that my communication attempt failed badly last time, so let me try again. The "standard" approach to indexicals is to treat indexical uncertainty the same as any other kind of uncertainty. You compute a probability of being at each location, and then maximize expected utility. I tried to point out in this post that because decisions made at each location can interact non-linearly, this doesn't work.

You transformed my example into a game theory example, and the paradox disappeared, because game theory does take into account interactions between different players. Notice that in your game theory example, the computation that arrives at the solution looks nothing like an expected utility maximization involving probabilities of being at different locations. The probability of being at a location doesn't enter into the decision algorithm at all, so do such probabilities mean anything?

Comment author: cousin_it 05 August 2009 09:14:20AM *  0 points [-]

Yes, they do. In this case you just got lucky and the probabilities factored out of the calculations. The general case where they don't necessarily factor out is called evolutionary game theory: indexical probabilities correspond to replicator frequencies, utility corresponds to fitness.

Comment author: Wei_Dai 08 August 2009 07:59:24AM 0 points [-]

I need to brush up on evolutionary game theory, but I don't see the correspondence between these two subjects yet. Can you take a standard puzzle involving indexical uncertainty, for example the Sleeping Beauty Problem, and show how to solve it using evolutionary game theory?

Comment author: cousin_it 12 August 2009 02:53:24PM 0 points [-]

Hmm, I don't see any problem in that scenario. It doesn't even require game theory because the different branches don't interact. Whatever monetary rewards you assign to correct/incorrect answers, the problem will be easy to solve by simple expected utility maximization.