 Functionalists’ accounts of preferences deny such an intrinsically mental interpretation of preferences, without reducing them to behaviour. In functionalism, the nature of preferences, like that of other mental states, is determined by what roles they play – e.g. in evaluating choice alternatives, and in motivating actions. Yet who assigns these roles, and what justifies such assignments? Most authors agree that it is “the ontological commitments of our best theory or theories in the relevant area” that perform this assignment (List and Dietrich 2016, 257). How preferences are individuated, then, is dependent on the purposes for ascribing them. For example, revealed preferences are considered real if they are non-redundantly useful for describing regularities in an individual’s behaviour: