Is Natural Selection a Population-Level Causal Process?

Abstract

AbstractRecent discussions of natural selection focus on two questions: first, is natural selection a causal process or is it a statistical consequence of lower-level events? And second, is natural selection at the population level or at the level of individuals? Bouchard and Rosenberg (Br J Philos Sci, 55:693–712, 2004) argue that natural selection is causal and at the level of individuals, as opposed to Matthen and Ariew (J Philos, 99:55–83, 2002) and Walsh et al. (Philos Sci, 69:452–473, 2002), who argue that natural selection is at the population level and purely statistical. In addition to these two polar extreme positions, Millstein (Br J Philos Sci, 57:627–653, 2006) tries to steer a middle course by arguing that natural selection is a population-level causal process. I will make three points in this chapter: first, Millstein’s account of natural selection is incomplete, in the sense that nowhere in her account can one find a place for cases of natural selection-of. Second, we should prefer Brandon’s account of natural selection and drift over Millstein’s, on the grounds that her account fails to meet a plausible requirement that Brandon’s account succeeds in meeting: namely, whenever natural selection and drift operate together, a change in the strength of natural selection implies an inverse change in the strength of drift, and vice versa. Third, the prospects of the view that natural selection is a population-level causal process depend on a satisfactory solution to both the epiphenomenon and the overdetermination problems. With the help of an analogy, I will show how the two problems can be dealt with.KeywordsNatural SelectionReproductive SuccessSampling ProcessEffective Population SizeSmall OrganismThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.