The Life of the Mind attempts to characterise two of three basic activities of mental life:Thinking (volume 1) and Willing (volume 2). Sadly, Arendt died before producing a third volume she had planned on what she saw as the third activity ‘Judging’.

Thinking is divided into four parts: ‘Appearance’ (I), ‘Mental Activities in a World of Appearances’ (II), ‘What Makes Us Think?’(III), and ‘Where Are We When We Think?’(IV). Part I is broken down into eight subsections (Sections 1-8). In Section 1, Arendt discusses the phenomenal character of the experienced world, its diversity; what it is to be alive; and the primacy of appearance for all living things. Appearances can only be fled into other appearances. In Section 2 she examines ‘being and appearance’ (i.e., ‘the two-world theory’). Theories that depend on this dichotomy are seen as resting on a logical fallacy. Section 3 sets out to re-establish the depth of the inner life over the tendency to devalue it in the tendency toward metaphysical commitments. Of particular note, Arendt discusses the Swiss biologist Adolf Portmann to make her case. Section 4 discusses the inner life and the relationship of body and soul, discussing Aristotle, the urge toward self-display, its connectedness with self-awareness, and the distinction between self-display and sheer being. Section 5 discusses semblance as a consequence of a world of appearances, with Section 6 discussing Kant around this subject, while also paying particular attention to the thinking ego and the self. Section 7 is concerned with the thinking ego and reality, focusing on Cartesian doubt and the Common Sense. The thinking ego gives rise to doubt and scepticism about self and other, and reality is ‘guaranteed’ by commonness (comprised of three elements). Common sense reasoning enables our survival. Section 8 concludes Part I and looks at the connection between science and common sense, again returning to Kant and pointing out the role and importance of Kant’s distinction between reason (Vernunft) and intellect (Verstand).

Part II, ‘Mental Activities in a World of Appearances’, contains five subsections, numbered 9-13. Section 9 reidentifies the three basic mental activities (thinking, willing and judging), which have the characteristic of invisibility and which enable humanity’s setting apart (withdrawal) from the world of the merely living. Section 10 tracks the conflict between common sense and speculative thinking apparent in the mind of the philosopher, discussing in particular Hegel as a philosopher exemplifying, as well as testifying, to this conflict. Section 11 examines the relation of thinking and doing, raising a problem concerning the location of the mind as spectator, and Section 12 investigates language and metaphor: analogy, metaphor, and symbolic uses of language enable us to elaborate what can be said but not seen and guarantee the unity of human experience. Section 13 discusses metaphor and the ineffable: language is the medium through which the invisible (mental life) is made manifest in the world of appearances. Thinking depends entirely on metaphors bridging the gulf between appearance and the thinking ego. However, there is no metaphor that can illuminate this activity of mind.

Part III, ‘What Makes Us Think?’ is comprised of five subsections, 14-18. Section 14 turns to the prephilosophic assumptions of Greek philosophy in relation to the question ‘what makes us think?’ Section 15 addresses Plato’s answer to this question, Section 16 is concerned with the Roman answer, and Section 17 with Socrates’ answer. In Section 18, Arendt raises the question as to where these solutions leave us in relation to one of her starting problems, that is, the possible interconnection between nonthought and evil (an insight she drew from Eichmann’s trial and wrote about in The Banality of Evil).

Part IV, ‘Where Are We When We Think?’, is composed of three subsections. Section 19 contains a brief summary of some of the most important of her reflections in the preceding divisions, before raising some concerns about the question concerning the location of the thinking ego. Section 20 makes some reflections upon the potential of its temporal location, and Section 21 concludes the treatise with some prospective considerations concerning the planned future volumes.