The Bar Fight Theory of International Conflict: Regime Type, Coalition Size, and Victory

Abstract

Studies of regime type and war have shown that democracies tend to win the wars they fight, but questions remain about why this is the case. A simple, if under-appreciated, explanation for democratic victory is that democracies fight alongside larger and more powerful coalitions. Coalition partners bring additional material capabilities and may provide intangible benefits to the war effort, such as increased legitimacy or confidence. Democracies may also find coalitions less costly or constraining, even as democratic war aims may be easier to apportion among the victors without diluting the spoils. Evaluating our hypotheses in a sample of all wars (or all militarized disputes) during the period 1816-2000, we find that democracies have more coalition partners when they fight, and that states fighting with more numerous coalition partners are more likely to win major contests. This finding is robust to replacing the number of coalition partners with the cumulative military power of those partners. Non-democracies also gain a likelihood-of-victory benefit with additional partners, but they appear less willing or able to form large military coalitions. Finally, we show that the indirect effect of democracy on success in war through coalition size subsumes much of the direct effect previously attributed to regime type.