This chapter describes the standard assumption of rational-choice institutionalism, according to which voters should be seen as being self-interested and fully rational. Public-Interest–Oriented Citizens is indeed plausible to think that much or most public debate about public-policy issues is ostensibly oriented toward criteria of common interest and distributive justice rather than about individual or even group self-interest. They would have to be supported and qualified by showing under which conditions the outcomes obtained by majority vote can also be justified in the light of output-oriented criteria. For collectively binding decisions, therefore, democratic procedures are essential in input-oriented arguments, whereas they have only instrumental value in the context of output-oriented arguments. Input-oriented legitimacy arguments, by contrast, imply that authentic agreement, though not necessarily assuring effective implementation by itself, is nevertheless able to create an obligation to comply—and hence to legitimate the enforcement of compliance.