The Invention of Duty: Stoicism as Deontology by Jack Visnjic (review)

philosophers’ broader philosophical views. Chapter 8 reintroduces a prominent example of this phenomenon from chapter 3—the difficulties that constitutive relativity creates for the theory of the Forms—and persuasively reconstructs one of Aristotle’s arguments against the Forms in On Ideas as a valid reductio, based only on assumptions about the nature of relativity that are shared by Aristotle and his Platonist targets. Chapters 9 and 10 take up the Stoic treatment of relatives. Chapter 9 provides a constitutive reading of two kinds of relatives that the Stoics distinguished. “Relatively disposed things,” like “father,” are directly constituted by a relation, whereas “differentiated relatives,” like knowledge and perception, are directly constituted by a power that is, in turn, constituted by a relation to its correlative. Chapter 10 then surveys the philosophical uses the Stoics may have made of these notions. For instance, Duncombe finds a role for differentiated relatives in the Stoic account of mixture and makes illuminating use of his account of relatively disposed things in reconstructing a debate between Aristo and Chrysippus about the unity of virtue. The study concludes with Sextus Empiricus, who, according to Duncombe, operates with a “conceptual” view of relativity in his arguments against his dogmatic opponents. The conceptual view modifies the standard constitutive view by introducing the qualification that a relative “is constituted by being conceived relative to something” (244). Duncombe suggests that Sextus moves to the conceptual level because the standard constitutive views involve claims about the natures of relatives—claims that Sextus, as a Pyrrhonian Skeptic, cannot endorse (245). This is an intriguing example of Duncombe’s third major thesis in the book, that philosophers’ larger philosophical outlooks affected their views of relativity (249), but I found myself wondering whether this explanation for Sextus’s innovation is consistent with the idea that skeptics speak without endorsing the claims they make (PH I,13; 192–93), which Duncombe invokes in claiming that Sextus’s commitment to conceptual relativity is purely dialectical (233, 237). If Sextus’s remarks about relativity are purely dialectical, considerations about what Sextus, as a skeptic, can and cannot endorse should be irrelevant. This book is a rare kind of achievement in ancient scholarship, dealing as it does with a subject that is understudied and yet, as Duncombe convincingly shows, indispensable for properly understanding ancient philosophical thought on many key topics. Given the range of problems on which the book makes new progress, it will be a rewarding read for just about anyone working on Greek philosophy. I a n J . C a m p b e l l Humboldt-Universität zu Berlin