Christie, Brusse, et al. argue that selected effects are insufficient to explain the prevalence of traits when selection is heterogeneous. One could object that it’s useful to ground functions in selected effects so long as selected effects are necessary to explain the prevalence of traits. This raises a challenging question: what justifies singling out selected effects from other factors that are necessary to explain the prevalence of traits when selection is heterogeneous? I consider three answers: selected effects are the only (...) factors that explain the prevalence of traits and (a) can plausibly ground functions; (b) enable biological generalization; and (c) enable representational explanation. I argue that none of these answers is satisfactory. Only the third answer might be able to justify singling out any selected effects at all (when selection is heterogeneous): the small share of selected effects that ground representations of causal particulars. Thus, I agree with Christie, Brusse, et al. that heterogeneous selection is a serious problem for selected effects theories of function. (shrink)

In the target article for this issue, Christie, Brusse, et al. [2022a] argue that Selected Effects Functions (SEF), at least as currently articulated, often do not explain biological traits. In res...