Utilitarian foundations for limited government are shaky insofar as they assume rational and consistent individuals. Recently economists' assumption of rational actors has come under sustained attack. Behavioural economics has suggested that people are plagued by irrational biases and inconsistencies. The author elucidates how these developments have led to a post-utilitarianism which is held to justify paternalistic interventions by the state via 'sin taxes', direct bans or new obligations. Individual responsibility is seriously undermined, as is faith in markets. He concludes that supporters of individual freedom need to move away from utilitarian reasoning, reassert core values of autonomy and responsibility, and define strict limits on the scope of government intervention.