CEFISES EH Seminar - Johannes Martens - The principle of natural selection as a ceteris paribus law (May 15)

Johannes Martens (UCLouvain), The principle of natural selection as a ceteris paribus law

Evolutionary biology is often regarded as a purely historical science—which, unlike physics, does not derive its explications from the existence of a set of specific laws. According to this conception, most of what occurs in the living world is the result of contingent processes acting on ever-changing populations, and there is no fundamental tendency acting directionally on some property of biological organisms (Beatty 1995). In the philosophical and biological literature, however, an alternative conception has been suggested, according to which evolutionary biology should be envisaged on the model of a “theory of forces” (Sober 1984). One key feature of this approach is that it represents the main causes of evolution, like natural selection, in the form of ceteris paribus (cp) laws—that is, as non-contingent explanatory statements whose truth holds only provided “other things remain equal” (Cartwright 1979). In the case of natural selection, the scope of such a (cp) clause should cover, ideally, the numerous genetic and ecological factors susceptible of preventing this process from driving the optimal phenotype to fixation in a given population. Yet, an immediate objection is that its content cannot be specified in a way that is both sufficiently informative and general. In the history of evolutionary biology, there has been one noteworthy attempt of capturing the core adaptive engine of evolution in the form of a ceteris paribus statement: the so-called “fundamental theorem of natural selection” (Fisher 1930). In this talk, I will focus on some of its recent interpretations (Okasha 2008), and argue that none can support a clear nomological interpretation of the principle of natural selection—even when the cp-clause has been correctly specified.