From Homo Economicus to Homo Psychologicus: the Paretian Foundations of Behavioural Paternalism

Behavioural paternalism aims at designing public policies helping boundedly rational individuals to satisfy their own preferences. It is assumed that (i) individuals have true preferences which would determine their choices if they were rational, (ii) the satisfaction of those preferences constitutes the normative criterion, and (iii) it is possible to elicit those preferences from the social planner standpoint. I argue that behavioural paternalism implicitly endorses Pareto's model of the Homo economicus, and highlight the methodological difficulties of those three hypotheses. My main argument is that behavioural paternalists cannot define unambiguously what would be the preferences of an ideally rational agent.