The Life of the Mind was Arendt's attempt to give the vita contemplativa the systematic treatment she had given the vita activa in The Human Condition. She planned three volumes — on thinking, willing, and judging — corresponding to the three mental activities she considered irreducible. She completed the first two before her death in December 1975; the third existed only as lecture notes, later published as Lectures on Kant's Political Philosophy (1982). The work developed the distinction between thinking and cognition that became central to the Arendt simulation's diagnosis of the AI age, and extended her earlier concept of thoughtlessness into a positive account of what thinking is and what it accomplishes.
The book's origin lay in the Eichmann controversy. Arendt had identified Eichmann's thoughtlessness as the mechanism of his evil, and she wanted to articulate more rigorously what thinking was such that its absence could have such consequences. The resulting work is philosophically dense, drawing on Plato, Aristotle, Augustine, Kant, Hegel, and Heidegger, and it marks Arendt's most sustained engagement with the philosophical tradition.
The first volume, Thinking, developed the distinction that matters most for AI. Thinking, Arendt argued, is the two-in-one internal dialogue — the soundless conversation with oneself that Socrates called the activity of the thinking ego. It has no external product, no goal beyond its own continuation, and no criterion of success other than the coherence of the thinker with herself. Cognition, by contrast, aims at knowledge of objects and is governed by external standards of truth.
The second volume, Willing, traced the history of the Western concept of will from Paul through Augustine to Nietzsche and Heidegger. It concluded with an analysis of the will's characteristic experience of the new — the capacity to initiate, which Arendt connected back to natality.
The projected third volume, on Judging, was to have completed the trilogy by articulating the mental activity that mediates between thinking and willing and makes political life possible. Arendt's death left the systematic treatment unfinished, and her interpreters have spent four decades reconstructing what the volume would have argued from her lecture notes and scattered remarks.
Arendt conceived the project in the late 1960s and delivered parts as the Gifford Lectures at the University of Aberdeen in 1973. She was working on the Judging volume when she died at her apartment on Riverside Drive in December 1975; Mary McCarthy edited the completed volumes for publication by Harcourt Brace in 1978. The lecture notes on Judging were edited by Ronald Beiner and published as Lectures on Kant's Political Philosophy in 1982.
Three mental activities. Thinking, willing, and judging are irreducible — each with its own logic and its own relationship to the world.
Thinking without product. The activity of thinking produces no external artifact; its value is internal to the activity itself.
Willing as beginning. The will is the mental faculty that corresponds to natality — the capacity to initiate.
Judgment unfinished. The systematic treatment of judgment Arendt planned was never written; her framework remains open on this crucial question.