The phrase “the banality of evil” is frequently attributed to Arendt’s final passage in Eichmann in Jerusalem. In this work, Arendt describes watching Adolf Eichmann’s execution and how, even as he faced imminent death, Eichmann could only offer the stock phrases and ideologies that had been fed to him. The full quotation calls Eichmann’s wickedness the “word-and-thought defying banality of evil.” Arendt’s use of “banality” in this quotation refers to the unoriginality of evil and its reliance on repetition and mimicry.

In philosophy, “Being” is a fundamental concept that refers to what it means for something to be, not to a specific entity. Since antiquity, philosophers have debated how we can understand Being and whether it is stable or changing. For Plato, Being was the realm of the eternal, unchanging Forms that underlie the apparent world. Arendt traces the history of how philosophers have conceptualized Being, and she is critical of those conceptions which give primacy to Being over appearance.

The Eichmann trial, detailed in Arendt’s book Eichmann in Jerusalem, was a trial in front of the Israeli Supreme Court in 1961 in which Adolf Eichmann, a senior Nazi member, was sentenced to execution. Arendt uses the trial to frame her ideas about the thoughtlessness of evil and the association between thinking and morality.

The doctrine of eternal recurrence is one of Nietzsche’s concepts which imagines that all events in life will repeat themselves endlessly. Arendt engages eternal recurrence in her discussion of the Will, comparing Nietzsche’s approach to the philosophers of antiquity. Arendt challenges Nietzsche, arguing that humans have the ability to interrupt, to create anew, and to start again.

Metaphysics is a branch of philosophy that looks beyond the physical world of appearances to study the nature of being and universal truths. The linear focus of the philosophical tradition on the metaphysical stems from Plato, but Arendt diverges from this tradition. She argues that it is a mistake to overlook appearances and worldly experience.

Phenomenology is a 20th-century philosophical movement that emphasizes the careful description of phenomena—the way things appear to consciousness. It is a focus on the apparent world rather than the metaphysical realm. Heidegger transformed phenomenology into an inquiry about Being itself, arguing that human existence discloses Being through everyday activities. Like her mentor, Arendt appreciates phenomenology’s attention to appearances and lived experiences, but she emphasizes the worldly and political elements and the importance of the thinking ego.

The Allegory of the Cave, which appears in Plato’s Republic, describes prisoners chained in a cave who can see only shadows cast on the wall in front of them. Mistaking these shadows for reality, they live in ignorance. If one prisoner were freed, he would gradually come to see the fire behind him that is responsible for casting the shadows on the world. He would also eventually see the world outside the cave, illuminated by the sun which symbolizes truth. Arendt uses Plato’s allegory to explore how philosophers have traditionally given primacy to truth.

Hannah Arendt’s concept of the vita activa, developed in The Human Condition (1958), refers to the active life of human beings engaged in the world through three fundamental activities: Labor, work, and action. Labor is a biological necessity that drives the maintenance of everyday life, and work creates the durable world. Arendt considers action to be the highest form of activity. It allows humans to establish relationships with others through plurality, experience freedom, and embark on a political life.