The book explores the period from the early Enlightenment to the late 20th century through discussions of philosophers who often figure in traditional histories of philosophy, such as Leibniz, Kant, Hegel, Nietzsche, and Schopenhauer, as well ones who do not, such as Pierre Bayle, Sigmund Freud, Albert Camus, Emmanuel Levinas, and Hannah Arendt. Neiman groups thinkers around two basic distinctions: one between those who believe in a guiding order beyond appearances and those who think that sensory experience is all we have for orientation; and another between those who believe we must try to understand evil and those who maintain that doing so would be immoral on the grounds that any explanation of evil would be tantamount to its justification.