p4wnc6 comments on Absence of Evidence Is Evidence of Absence - Less Wrong

54 Post author: Eliezer_Yudkowsky 12 August 2007 08:34PM

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Comment author: p4wnc6 14 June 2011 04:44:02AM *  1 point [-]

I see your point and I think we mostly agree about everything. My only slight extra point is to suggest that perhaps Warren was trying to use his prior beliefs to predict an explanation for absence of sabotage, rather than trying to use absence of sabotage to intensify his prior beliefs. In retrospect, it's likely that you're right about Warren and the quote makes it seem that he did, in fact, think that absence of sabotage increased likelihood of Fifth Column. But in general, though, I think a lot of people make a mistake that has more to do with starting out with an unreasonable prior, or making assumptions that their prior belief is independent of observations, than it has to do with a logical fallacy about letting conditioning on both A and ~A increase the probability of B.