Autonomous-Statistical Explanations and Natural Selection

Shapiro and Sober ([2007]) claim that Walsh, Ariew, Lewens, and Matthen (henceforth WALM) give a mistaken, a priori defense of natural selection and drift as epiphenomenal. Contrary to Shapiro and Sober's claims, we first argue that WALM's explanatory doctrine does not require a defense of epiphenomenalism. We then defend WALM's explanatory doctrine by arguing that the explanations provided by the modern genetical theory of natural selection are 'autonomous-statistical explanations' analogous to Galton's explanation of reversion to mediocrity and an explanation of the diffusion of gases. We then argue that whereas Sober's theory of forces is an adequate description of Darwin's theory, WALM's explanatory doctrine is required to understand how the modern genetical theory of natural selection explains large-scale statistical regularities.