The Ripple Effects of the Illegitimacy of War

s Recent data show systematic changes in the diplomacy and practice of war. Conquests, peace treaties, declarations of war, and state boundary changes have declined or disappeared. There are still wars, but they are increasingly fait accomplis, and their outcomes are often not recognized as legal. How can we explain this wide-ranging but seemingly contradictory transformation? Existing accounts, such as those based on a territorial integrity norm, do not adequately explain these changes. This paper uses norm dynamics theory to show that all of these changes can be explained as ‘ripple effects’ of war becoming illegitimate as a way to solve international disputes. The kinds of rhetorical justifications states can convincingly give for engaging in violence have changed. States are navigating this changed international social environment through legitimacy management behaviors. The paper specifies three types of ripple effect, Reframing, Displacement, and Consistency-Maintenance, corresponding to changes in what states say, the actions they perform, and how the audience reacts. We show how this theory unifies all of the existing data into a single explanatory framework. We also apply the theory to the decline of peace treaties to show how ripple effects play out in more detail.