Thorton Lockwood, "Cicero: Just War Philosopher"

Cicero’s On Duties (de officiis [Off.]) provides an account of the duties of justice that includes the duties of warfare or armed conflict (iura belli [Off. I.34-40]) that is remarkable for a number of reasons. First, although political philosophers like Plato and Aristotle provide reflections on the normativity of armed conflict (for example, Republic 5: 466d-471e or Politics 7.1-3), they fail to provide any systematic theory or philosophy of just war. Cicero’s account is thus the first systematic philosophy of armed conflict. Second, although Cicero claims that the structure of On Duties derives from the Stoic philosopher Panaetius (Off. 1.9), I argue that Cicero’s account of the duties of armed conflict is so clearly immersed in the military practices of the Roman Republic that it is unlikely to attribute this part of On Duties to Panaetius. Rather, Cicero’s account of just war seems unambiguously his own philosophy, grounded in reflection on Roman exempla, rather than one that he has received from Stoic sources and which he subsequently illustrated with Roman exempla. Finally, Cicero’s account of the duties of armed conflict clearly includes the conceptual distinction between what the subsequent just war tradition entitles the conditions of just war (ius ad bellum) and the conduct of just war (ius in bello) in a fashion more clearly and decisively than any thinker prior to Hugo Grotius.