Functions and Populations: Sharpening the Generalized Selected Effects Theory of Function

The generalized selected effects theory of function (GSE) holds that a trait’s proper function is an activity that historically caused its differential persistence or differential reproduction within a population, construed as a collection of individuals that impact each other’s persistence or reproduction chances. Several critics have taken aim at GSE on the grounds that its appeal to populations is either unfit for purpose or arbitrary. Here I revise GSE by articulating a notion of population that is fit for purpose and showing that its selection is not arbitrary but flows from the realist commitments of the selected effects theory.