This thesis develops Arendt's concept of "the public" as the necessary condition for the practice of politics. Through an engagement with both the notion of plurality, which lies at the core of Arendt's thought, and her concepts of common sense and the world, it understands the Arendtian public realm as the combination of both public space and public spirit. This not only distinguishes Arendt's concern for politics from the Habermasian sociological-institutional model, but equally explains some of her more contentious arguments about modernity. In the 'dark times' of totalitarian rule, the public spirit is left without a public space. Conversely, the condition of 'the social' is better understood as public space without public spirit. This thesis, as an examination of the conditions of politics, clarifies a key strand of Arendt's work while laying the groundwork for an analysis of Arendt's thoughts on the practice of politics itself.