This paper argues that a minimal notion of function and a notion of normal-proper function are used in explaining how bodies and brains operate. Neither is Cummins’ notion, as originally defined, and yet his is often taken to be the clearly relevant notion for such an explanatory context. This paper also explains how adverting to normal-proper functions, even if these are selected functions, can play a significant scientific role in the operational explanations of complex systems that physiologists and neurophysiologists provide, (...) despite a lack of relevant causal efficacy on the part of such functions. (shrink)

The selected effects or ‘etiological’ theory of Proper function is a naturalistic and realist account of biological teleology. It is used to analyse normativity in philosophy of language, philosophy of mind, philosophy of medicine, and elsewhere. The theory has been developed with a simple and intuitive view of natural selection. Traits are selected because of their positive effects on the fitness of the organisms that have them. These ‘selected effects’ are the Proper functions of the traits. Proponents argue that this (...) analysis of biological teleology has the unique advantage that the selected effect function of a trait is also a causal explanation of the trait: the trait exists because it performs this function. We show, however, that selected effect functions as currently defined explain the existence of traits only under highly restrictive assumptions about evolutionary dynamics. In many common scenarios in which traits evolve by natural selection, selected effect functions do not explain those traits. This is because definitions of selected effect function extract from any evolutionary scenario only the information that would be explanatorily relevant in the simple evolutionary scenario implicit in those definitions. When applied to more complex scenarios, selected effect functions omit the key information that is explanatorily relevant in those scenarios. The assumptions required for selected effect functions to be explanatory are particularly unlikely to hold in the domain that its proponents care most about—the evolution of representation. A more adequate selected effects theory of Proper functions may be possible, but will require much greater attention to the structure of actual evolutionary explanations. (shrink)

In ‘Are biological traits explained by their “selected effect” functions?’, Christie, Brusse, Bourrat, Takacs, and Griffiths argue that selected effect functions only explain the presence of a trait (or the frequency of a trait in a population) in cases in which the selective environment has been uniform, illustrating their point with cases of coevolution, frequency-dependent selection, and bet-hedging. This commentary suggests that selected effect functions are explanatory even in those cases, and that Christie, Brusse, et al. are mistaken about the (...) explanatory aims of the selected effects theory, criticizing it for failing to do something it never set out to do. (shrink)

In the target article, Christie, Brusse, et al. argue that selected effect functions do not, in general, explain why a trait exists in a population and, therefore, theories of representational content should not rely on selected effect functions. This response focuses on the claim about functions-for-representation. The role of evolutionary functions in a theory of content is to pick out outcomes that have been systematically stabilized by natural selection. Correctness conditions are conditions involved in explaining how that happened. Selected effect (...) functions can play that role in the complex equilibria that Christie, Brusse, et al. identify. Non-equilibrium cases are also discussed. (shrink)

Christie, Brusse, et al. claim that the ‘selected effect’ (SE) theory of function is premised on a simplistic view of evolution. In complex evolutionary scenarios, in particular those involving frequency-dependent selection (FDS), the SE theory fails, they argue, since citing a trait’s SE function does not serve to explain why the trait exists. I argue that where FDS leads to a stable equilibrium, at which all individuals’ trait values constitute a ‘best response’ to the rest of the population, the SE (...) theory can be straightforwardly applied. However, matters are different if the evolutionary dynamics do not take the population to a stable equilibrium. (shrink)

Christie, Brusse, et al. argue that the selected effects theory of function (SE) doesn’t do what it’s supposed to do: namely, show how functions can be explanatory. They survey some well-known evolutionary dynamics such as arms races, frequency-dependent fitness, and environmental heterogeneity, some of which have been discussed in the functions literature for decades. They argue that SE only seems to work because SE theorists ignore these dynamics. Their argument fails because they misrepresent what functions are supposed to explain and (...) how they’re supposed to do so. One reason for this failure is that they overlook the role of functions in the broader conversation about teleology in biology, one that has been unfolding for over 2000 years. (shrink)