Proper Functions as Selected Effect Functions of Fixed Traits

Abstract This article proposes restricting selected effect (SE) proper functions to effectively fixed traits—traits at or close to fixation in the population. SE functions, as historical fitness contributions in general, can only ground gradual normative standards at the character-state level, whereas proper functions are further expected to ground a stronger normativity at the character level. Proper function thus requires the trait’s fitness contributions to be sufficiently strong and sustained, and fixation provides a principled standard for such contributions. The restricted account better addresses the explanatory challenge to proper functions while preserving their theoretical goals of grounding robust teleology and normativity.