Perplexed comments on St. Petersburg Mugging Implies You Have Bounded Utility - Less Wrong

10 Post author: TimFreeman 07 June 2011 03:06PM

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Comment author: Perplexed 10 June 2011 10:31:09PM 0 points [-]

Yes, I understand conditional and unconditional convergence. What I don't understand is how you get conditional convergence from

... if there was a 2^-n chance of getting 2^n utility and a 2^-n/n chance of getting -2^n/n utility (before normalizing)

I also do not understand how your "priors don't allow that to happen".

It almost seems that you are claiming to have unbounded utility but bounded expected utility. That is, no plausible sequence of events can make you confident that you will receive a big payoff, but you cannot completely rule it out.

Comment author: DanielLC 11 June 2011 06:47:17AM 0 points [-]

What I don't understand is how you get conditional convergence from ... ... if there was a 2^-n chance of getting 2^n utility and a 2^-n/n chance of getting -2^n/n utility (before normalizing)

I just noticed, that should have been 2^-n chance of getting 2^n/n utility and a 2^-n chance of getting -2^n/n

Anyway, 2^-n*2^n/n = 1/n, so the expected utility from that possibility is 1/n, so you get an unbounded expected utility. Do it with negative too, and you get conditionally converging expected utility.