Abstract: Behavioural economics offers a critique of modern neoclassical economics by providing empirical evidence that the model of rational choice does not accurately describe human decision-making processes. The existence of cognitive biases, what we might term ‘agent failure’, becomes reason to doubt the efficacy of unhampered markets, and is seen by some as a sufficient condition for government intervention. This article offers a critique of this argument from an Austrian and public choice theory comparative institutions perspective. Agent failure arguments are analogous to market failure arguments of the mid-twentieth century and the same kinds of responses made against the latter are applied to the former. Behavioural economics arguments for intervention ignore the cognitive biases of political actors, neglect the comparative perspective that results from such biases, and do not examine the ways in which markets are superior to politics in providing the information and incentives actors need to become aware of their errors and correct them. The existence of imperfectly rational agents, like the existence of imperfect markets, is therefore not a sufficient condition for government intervention into the market.