This chapter considers relevant concepts and paradigms elaborated in Hannah Arendt’s works, which have been at the centre of modern and contemporary Western political thought even beyond Arendt. It explores the relation between truth, lying, and politics in contemporary democracies. In her reflection on Truth and Politics, Arendt distinguishes between factual truths and rational truths to specify the different relations they have with the political debate in a plural society and to investigate the consequences of their negation or mystification. Factual truths, while being at odds with the political debate, are necessary for the exercise of democratic power in a plural society. Also, this is the category which acquires critical relevance today with reference to the problem of fake news: it is factual truths that fake news denies. Arendt is quite optimistic about the fact that, as long as there are witnesses and truth-tellers, in the long run truth will outlive organised lying.