It is difficult to read both the theoretical literature in political science on the causes of war and historians' case studies of the origins of particular wars without being struck by the difference in their respective evaluations of the importance of domestic political factors. Whereas historians devote considerable attention to these variables, most political scientists minimize their importance. Domestic political variables are not included in any of the leading theories of the causes of war; instead, they appear only in a number of isolated hypotheses and in some empirical studies that are generally atheoretical and noncumulative. This gap is troubling and suggests that political scientists and historians who study war have learned little from each other. A greater recognition of the role of domestic factors by political scientists would increase the explanatory power of their theories and provide more useful conceptual frameworks for the historical analysis of individual wars.

This study takes a first step toward bridging this gap by examining some of the disparate theoretical literature on domestic politics and war. It examines the relationship between national attributes and war behavior, the relative likelihood of democratic and non-democratic regimes going to war, Marxist and liberal theories regarding the impact of economic structure, the influence of nationalism and public opinion, and the scapegoat hypothesis. First, however, this article takes a closer look at the different treatment of domestic sources of war by political scientists and historians.