Multiple Realization and Evolutionary Dynamics: A Fitness-Based Account

Abstract

Multiple realization occurs when a natural kind is variably realized at more basic levels and the common physical structure of the realizers is not essential for supporting nomological statements. It has been suggested that this phenomenon may be an outcome of natural selection acting over multiple realizers that perform an adaptive function. In this paper, we make the following contributions. First, we present a revision of this model, characterized by stricter equilibrium conditions and superior explanatory power. Second, we present a typology of multiple realization that provides a plausible account of the differences between across- and within-species multiple realization. Third, we perform a formal analysis of the dynamics of multiple realization that sheds light on the differences between multiple realization at different levels of organization.