Liberalism requires a high order of responsible behaviour from its citizens in order to be sustainable. Yet when the modern liberal state makes policy, it is the stereotyped 'economic man', driven by self-interest and influenced only by carrots and sticks, who occupies center stage. This regulatory approach to public policy can be shown theoretically to give rise to a paradox - the greater the need for regulation, the less likely, because of compliance problems, it is to succeed. It is contended that an alternative approach which explicitly focuses on a broader behavioral understanding of citizens' attitudes and motivations provides a rationale for the use of a much wider range of policy instruments than does the regulatory framework, and is also more in keeping with those values necessary to the sustainability of the liberal state.