Nationalism, so far the most potent principle of political legitimacy in the modern world, holds that the nation should be collectively and freely institutionally expressed, and ruled by its conationals. In numerous essays and four books, Ernest Gellner, an exceptionally brilliant, fluent, prolific and witty philosopher, anthropologist, sociologist and multilingual polymath provided lucid and persuasive accounts of why nationalism is a necessary component of modernity, and why it is its typical and major principle of political legitimacy. This chapter seeks to provide a preliminary posthumous analysis of Gellner's legacy. It needs little justification since all worthwhile subsequent writing and research on nationalism will benefit from Gellner's work, whether they build on his presumptions or dissent from them.

Gellner's arguments about nationalism disturbed both conservatives and secular rationalists. The reasons are not hard to find. Nationalism relegates religion to a secondary, and even inessential, principle of a stable and legitimate political order and thus challenges traditionalist conservatism. Nationalism also suggests that law, reason, utility, material prosperity and social justice are secondary principles in establishing a stable and legitimate political order, and has therefore provoked persistent condemnation from rationalist liberals and socialists for some two hundred years. Gellner's writings on nationalism were a sustained criticism of one very pious Oakeshottian conservative, the late Elie Kedourie; but they were also intended to reassure rationalist liberals (including social democrats). One question is whether he provided the right reassurances.