   Empirical adaptationism is both a claim about the relative frequency of natural selection across evolutionary histories and about the power of natural selection to overcome constraints and contingency. Orzack and Sober's (1994a,b) ensemble test of the truth of empirical adaptationism is structured in the following way for any given trait, T. In order to contribute to the ensemble test, the analysis of the trait must allow the investigator to confirm one of the following hypotheses about the power of natural selection: