Leader similarity and international conflict

Scholars increasingly emphasize personal biographical characteristics of leaders in explaining patterns of foreign policy behavior. This article extends insights from this agenda to study how (dis)similarities in the background characteristics of leaders at the dyadic level shape international conflict outcomes. Trust and uncertainty are central to explaining conflict via their connections to commitment- and information-related causes of war. Psychological research provides evidence that perceived similarities between individuals and groups can foment trust and cooperation. We hypothesize that leaders who share more similar backgrounds and life experiences form stronger social bonds and are more trusting of one another. As such, leaders who have more in common with one another should be able to better manage diplomatic disputes and avoid conflict. We test this hypothesis using a new measure of dyadic-leader-level similarity created with the Leader Experience and Attribute Descriptions (LEAD) dataset and data on international conflict onset in politically relevant dyads throughout the period 1946–2004. We find that pairs of leaders with more similar backgrounds are significantly less likely to experience militarized interstate disputes at all levels of hostility even after accounting for a variety of observable and unobservable determinants of conflict. The findings contribute to our understanding of the determinants of international conflict and help advance research on linkages between psychological and rationalist approaches to studying conflict.