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Manfred comments on Pascal's Muggle: Infinitesimal Priors and Strong Evidence - Less Wrong

43 Post author: Eliezer_Yudkowsky 08 May 2013 12:43AM

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Comment author: Manfred 06 May 2013 09:48:47AM *  10 points [-]

Suppose we had a planet of 3^^^3 people (their universe has novel physical laws). There is a planet-wide lottery. Catherine wins. There was a 1/3^^^3 chance of this happening. The lotto representative comes up to her and asks her to hand over her ID card for verification.

All over the planet, as a fun prank, a small proportion of people have been dressing up as lotto representatives and running away with peoples' ID cards. This is very rare - only one person in 3^^3 does this today.

If the lottery prize is 3^^3 times better than getting your ID card stolen, should Catherine trust the lotto official? No, because there are 3^^^3/3^^3 pranksters, and only 1 real official, and 3^^^3/3^^3 is 3^^(3^^3 - 3), which is a whole lot of pranksters. She hangs on to her card, and doesn't get the prize. Maybe if the reward were 3^^^3 times greater than the penalty, we could finally get some lottery winners to actually collect their winnings.

All of which is to say, I don't think there's any locational penalty - the crowd near the muggle should have exactly the same probability assignments as her, just as the crowd near Catherine has the same probability assignments as her about whether this is a prankster or the real official. I think the penalty is the ratio of lotto officials to pranksters (conditional on a hypothesis like "the lottery has taken place"). If the hypothesis is clever, though, it could probably evade this penalty (hypothesize a smaller population with a reward of 3^^^3 years of utility-satisfaction, maybe, or 3^^^3 new people created), and so what intuitively seems like a defense against pascal's mugging may not be.