“The conjunction fallacy is when humans rate the probability P(A,B) higher than the probability P(B), even though it is a theorem that P(A,B) ≤ P(B). For example, in one experiment in 1981, 68% of the subjects ranked it more likely that “Reagan will provide federal support for unwed mothers and cut federal support to local governments” than that “Reagan will provide federal support for unwed mothers.”” (Eliezer Yudkowsky, Rationality)