Sober’s Use of Unanimity in the Units of Selection Problem

Abstract

The units of selection problem is an issue within evolutionary theory (or the philosophy thereof) and concerns the question of what units or objects are acted upon by natural selection -- for example, whether these are genes, organisms or groups of organisms. One of the central theses of Elliot Sober’s recent book, The Nature of Selection, is that the philosophical problem of what it means for something to be a unit of selection is to be understood by applying the correct account of what it is in general for a factor to be a cause in a population.The account of population-causation that Sober utilizes for this purpose comes from the recent literature on probabilistic causality. This account requires that for C to cause E in a population, a unanimity condition must be satisfied: C must raise the probability of E in each causal context.