The Hazard of War: Reassessing the Evidence for the Democratic Peace

In this article, we re-examine the statistical evidence for the democratic peace at the dyadic level. We also investigate the seeming paradox that democracies are engaged in war as often as autocracies at the nation level. From the extensive literature on democracy and peace we have selected as our point of departure two influential contributions (one by Stuart Bremer, the other by Zeev Maoz & Bruce Russett), both of which analyse the relationship between democracy and peace at the dyadic level. Several problematic aspects of these analyses are addressed; in particular, problems concerning dependence between observational units caused by continuing war and peace, and by diffusion effects. We show that the increasing number of countries in the international system causes their assumption of a stationary probability of war at the dyadic level to be violated. It is argued that these problems cannot be solved adequately within the traditional dyad-year framework. Instead, it is proposed to model observations on the interstate dyad as a process in continuous time using Cox regression. An extensive model is developed that controls for contiguity, power status, alliances, stability, diffusion of war, and recurrence effects. A concept of relevance is introduced to account for the dependence of the dyadic probability of war on the size of the international system. The democratic peace is supported in our basic model. In a refined model, we find that the tendency of democracies to join each other in wars is much more marked than their avoidance of mutual fighting. This explains why democracies are as war-prone as autocracies.