My substantive research in international relations focuses mostly on the causes of war and peace. My current research focuses on the question of whether, as other scholars have argued, interstate war is becoming more rare or even disappearing.

I also investigate two diametrically opposite models of conflict—the deterrence model, which suggests that conflict happens when deterrence fails; and the spiral model, which points to escalating spirals of hostility—that have long dominated security analysts’ thinking about the origins of war. I use my own systemic theory to test the deterrence model against the spiral model; the asymmetry of activity between Great Powers when disputes are initiated strongly suggests that the deterrence model is the more accurate of the two.

I also investigate the odd finding that the balance of capabilities between two states is irrelevant to territorial disputes. I show that the balance of capabilities between two states does predict the initiation or maintenance of a territorial claim, but only in combination with either systemic or dyadic incentives to fight.

I also focus on the impact of democracy and so-called “political irrelevance” on peace. In a study of the Soviet successor states, I show that liberalism is not always a force for peace. In a separate study (with Austin Carson), I show that nondemocracy and political relevance are near-necessary conditions for conflict.