Of Mice and Metaphysics: Natural Selection and Realized Population-Level Properties

Abstract

In this paper, I answer a fundamental question facing any view according to which natural selection is a population-level causal process—namely, how is the causal process of natural selection related to, yet not preempted by, causal processes that occur at the level of individual organisms? Without an answer to this grounding question, the population-level causal view appears unstable—collapsing into either an individual-level causal interpretation or the claim that selection is a purely formal, statistical phenomenon. I argue that a causal account of realization provides an answer to the grounding question. By applying this account of realization to the natural selection of melanism in rock pocket mice, I show how an alternative, formal account of realization, favored by proponents of the statistical interpretation, misses biologically important features. More generally, this paper shows how metaphysical issues about realization normally discussed in the philosophy of mind apply to debates in philosophy of biology. Thus, it is a first step toward fleshing out the oft-noted similarities between debates in these areas.