Geography, democracy, and peace

Several decades of systematic empirical work on the causes of war have generated a great many findings but few solid regularities. This article argues that there are two strong, known regularities: nations primarily fight proximate nations, and democracies rarely fight one another. The theoretical arguments and previous empirical evidence for each proposition are reviewed. Using the Correlates of War data on international war, data on democracy from Polity II, and inter‐capital distances generated from geographical coordinates, extensive empirical evidence for both propositions is given for the period 1816–1986. A hypothesis advanced by Small and Singer—that the lack of war between democracies might be accounted for by their proximity—is tested and rejected. While distance is a clear and pervasive influence on war during the entire period under study, double democracy has had lower explanatory power because of the low number of democracies. The importance of democracy lies in it being a near‐perfect sufficient condition for peace. Thus, as the number of democracies increases, lack of democracy will become a more important predictor to war.