Democratic theory, like democracy itself, comes in various shapes and sizes. There are today two leading theories of democratic legitimacy. Realist theorists such as Joseph Schumpeter and Robert Dahl focus on actual political institutions such as voting, competitive elections, and party elites. These are regarded as not only the necessary but also the sufficient conditions for democratic societies. Idealist theories of democracy typically draw inspiration from Jean-Jacques Rousseau, who focused on ways of enhancing citizen participation in deliberation and decision-making. A fully engaged citizenry, Rousseau believed, was a requirement for any theory of democratic legitimacy.