Published online by Cambridge University Press: 15 December 2022
I develop an account of ecological role functions—the functions of species within ecosystems—that is informed by alternative regime phenomena in ecology. My account is a causal-role theory that includes a counterfactual sensitivity condition. The account tracks and explains a distinction ecologists make between functions and various activities that are not functions. My counterfactual sensitivity condition resolves the liberality problem often attributed to causal-role theories of function while also illuminating the explanatory centrality of role functions within ecology.