Reading Arendt’s writings as exercises in political thinking, as opposed to reading them through a scholarly political theory or political science lens, exposes the enlightening potential and their practical power of Arendt’s political-philosophical project. As a political theorist she always keeps one goal in mind: to understand the common world and the political phenomena that are crystallized therein. This understanding is a foundation for any informed judgment. As the public sphere is a space that the persons acting in it share with one another, an element of plurality is always included in their activities. In the world, opinions must coexist in their diversity and neither action nor the power that derives therefrom can ever be understood as a matter of the individual. At the same time, political actors require the unifying power of the common world, without which their differences could only be expressed in parallel discourses instead of in public dialogue.

Political life therefore requires both the plurality of actors involved, with their diverse opinions and perspectives, and the common world as a space that connects them. Neither of these foundations is, in Arendt’s eyes, unconditionally guaranteed. Plurality is endangered not only by phenomena such as totalitarian rule, which oppresses individuality through coercion and indoctrination (OT 438), but also by the seemingly much less malign rise of mass society, in which everyone thinks and acts alike (HC 58). For its part, the common world, the space of appearance, is threatened due to the alienation of the individual inhabitants of the world: from themselves, from their activities, and from one another. Public discourse and political thinking dissolve into myriad individualistic perspectives that articulate a series of solipsistic worlds; which is to say: both totalitarian states and mass democracies give rise to a world in which there is no world in common.

Arendt relates this individualism and relativism to a tendency in twentieth-century social science to forgo clear distinctions and to define terms in a largely arbitrarily manner. She sees in this a danger not only for the possibilities of communication in the political realm but also for the constitution of the common world.