In the history of social and political philosophy, Hume has been characterised variously: as one of the forefathers of conservatism preceding Edmund Burke (Miller 1981; Livingston 1998); as a champion of (economic) liberalism together with Adam Smith (Hayek 1967); or as one of the precursors of the utilitarianism espoused by Jeremy Bentham (Rosen 2003: 48–57). The very variety of interpretations built up around Hume's social and political philosophy demonstrates how difficult it is to adequately explain his thought by reference to any one of these characterisations. This chapter will not aim to place Hume within any of these ‘isms’, but to make clear how and why such a variety of interpretation occurs by exploring the significant role that the concept of ‘opinion’ plays throughout Hume's political and historical writings. Hume refers to the notion of opinion on numerous occasions in his political essays; I will argue that he also uses it as a benchmark in the History of England. The concept of opinion is used both to exonerate the first two Stuart monarchs from blame, and to defend the Revolution settlement. For Hume, the notion of opinion was appropriate for both of these purposes, not in spite of, but because of its changeability. As Richard B. Sher correctly argues, ‘Hume's moral and political thought may now seem moderate and impartial, as it did to Hume himself, but from the Scottish Presbyterian viewpoint of his own day it looked very much like a series of potshots at cherished principles’ (1985: 66). To analyse the way Hume develops the thesis that every government is founded on opinion in order to both criticise and fundamentally modify the Whig ideology will help us to understand why some of his contemporaries regarded his claim as dangerous. Touching on Hume's thesis of opinion, Forbes timely asserts that ‘the ruthless application of experimental method to moral subjects was dangerously avant-garde– Hume's friends seem always to have realized this better than Hume himself– yet it was at the same time a post-revolutionary, establishment political philosophy’ (1975b: 91).