I read Kieran Setiya’s Midlife (Princeton, 2017) not only because I have that condition and am sometimes troubled by its complaints, but also because I appreciate the style of thought that Pierre Hadot named “philosophy as a way of life.” Practitioners of this style acknowledge that it is important to develop and test arguments. The philosophical life is one of critical reason. However, arguments should have a purpose: to improve a life. And we must remember that people are habitual and affective creatures. Therefore, arguments—no matter how valid and rigorous—will not change us. We also need practices or mental disciplines to accompany our arguments. But a mental habit or practice can lead us away from the findings of our critical reason. We may train ourselves to be foolish or selfish. So we need habits that are at least consistent with the best arguments, and, ideally, habits that actually include argumentation.
That is exactly the combination offered by the Hellenistic Schools (Stoicism, Epicureanism, Skepticism) and by the classical Indian traditions. It has been relatively weak in the modern West. Setiya shows that it can be practiced today.
He is a professional philosopher in the Anglophone, analytic tradition. A clue that he is trying something different in Midlife is the book’s grammar. Setiya often writes in the second-person singular: “You should …” (as in “You should not prefer to rewind time, erase your son, and try again.”) He also sometimes uses the first-person singular or plural: “I wish …”; “We think …” Midlife reads like a conversation that reports Setiya’s real efforts to combat his ennui in order to improve your life, too.
Midlife is almost free of jargon. But one person’s jargon is another’s helpful terminology, and Setiya makes occasional use of specialized words. His distinctive stylistic move is not his informal vocabulary but his shift to the second-person, which implies a stringent test that can be applied to each sentence and chapter: would an actual “you” find this text useful?
Another clue that Setiya is working in the tradition of philosophy as a way of life is that he recommends repeated practices, habits, or meditative exercises at the conclusion of each chapter. These are meant to turn the arguments of the chapter into therapies that might change our mental habits.
Many of Setiya’s recommendations are drawn from the history of ethics, not original to Midlife. Of course, that is fine; it is useful to review and revive others’ points. But some of his arguments are novel, and I will mention two.

