Optimality Modeling and Explanatory Generality

Abstract

The optimality approach to modeling natural selection has been criticized by many biologists and philosophers of biology. For instance, Lewontin (1979) argues that the optimality approach is a shortcut that will be replaced by models incorporating genetic information, if and when such models become available. In contrast, I think that optimality models have a permanent role in evolutionary study. I base my argument for this claim on what I think it takes to best explain an event. In certain contexts, optimality and game-theoretic models best explain some central types of evolutionary phenomena. The Optimality ApproachThe optimality approach offers a way to model natural selection purely phenotypically, without directly representing the system of genetic transmission. This approach includes both optimality models and game-theoretic models, which are used when trait fitnesses are frequency-dependent. One determines the range of possible values for some phenotype and the fitness function relating these phenotypes to the environment. Based on this information, the model predicts which phenotypic value(s) will predominate in the population, given enough time in that environment. Many instances of long term evolutionary change can be modeled in this manner, resulting in information regarding the effect of the selection pressure(s) at work and any constraints arising from, e.g., the process of genetic transmission or of development.

When does ‘Folk Psychology’ Count as Folk Psychological?

“…Instead of describing the way the world genuinely is, idealized models in science predict and explain phenomena by creating models of how the world ought to behave given various idealizations we build into our model, and then using this to draw inferences about the behaviour of real systems. Angela Consider, for instance, the role that optimality models play in evolutionary biology (Beatty [1980], [1981]; Orzack & Sober [1994], [1996]; Rice [2004]; Potochnik [2007], Woods & Rosales [2010]). Optimality models are commonly used to investigate and predict the evolution of phenotypic traits within a given population not by describing how the evolutionary process actually works (often ignoring known genetic and epigenetic factors in the evolutionary process), but instead only by characterizing what sorts of traits would be optimal for the creature to have given the constraints of natural selection.…”

Explanation in Biology

“…One example that has received much attention in the philosophy of biology is the case of equilibrium explanation (e.g., Sober 1983;Potochnik 2007). One example that has received much attention in the philosophy of biology is the case of equilibrium explanation (e.g., Sober 1983;Potochnik 2007).…”

“…32 31 See e.g., Potochnik (2007). But there is a further question of why biology in particular is so well-represented in discussions of MES.…”

Levels of Explanation Reconceived

“…So it is for genetic and phenotypic explanations of evolutionary phenomena (Potochnik 2007). A phenotypic explanation of a trait is applicable whenever the represented fitness relationship obtains, even if the genetic details vary.…”