This chapter describes Hannah Arendt’s The Origins of Totalitarianism. It presents some idea of the approach she takes to the subject, its strengths and its weaknesses. The texts in question are classic examples of ‘social contract theory’. Even Locke, whose argument most closely resembles the stereotypical portrait Arendt paints, is not open to the objection in question. One example of a factual claim made by Arendt – one that violates the principle – is her description of the concentration camps as ‘laboratories’. Mussolini regime was insufficiently ‘pure’ to count as totalitarian when assessed against Arendt’s criteria. Note that Arendt is offering a description of totalitarianism considered as an idea; that is, a pattern to which actual arrangements may correspond to a greater or lesser extent.