Abstract

I argue that there are at least four different ways in which the term ‘function’ is used in connection with the study of living organisms, namely: function as activity, function as biological role, function as biological advantage, and function as selected effect. Notion refers to what an item does by itself; refers to the contribution of an item or activity to a complex activity or capacity of an organism; refers to the value for the organism of an item having a certain character rather than another; refers to the way in which a trait acquired and has maintained its current share in the population. The recognition of a separate notion of function as biological advantage solves the problem of the indeterminate reference situation that has been raised against a counterfactual analysis of function, and emphasizes the importance of counterfactual comparison in the explanatory practice of organismal biology. This reveals a neglected problem in the philosophy of biology, namely that of accounting for the insights provided by counterfactual comparison.