 Prisoner (Nesson 1979). 100 prisoners are exercising in a prison yard. Suddenly 99 of them attack and kill the only guard on duty. One prisoner played no role whatsoever in the assault. These are the undisputed facts in the case, and there is no further information about what happened. If a prisoner is picked at random, his probability of guilt would be as high as .99. Yet the intuition is that this cannot be enough to establish guilt beyond a reasonable doubt.