  Few theorists after Thomas Hobbes and David Hume have argued that there is a general duty to obey the law or that political authority is generally legitimate (Hobbes 1668; Hume 1965). Most theorists have argued that the legitimacy of political authority is one that holds only when the political authority satisfies certain normatively important conditions. What we will review here are some of the main theories that attempt to explain when a political authority has legitimacy.