Explaining Wars Fought by Established Democracies: Do Institutional Constraints Matter?

Abstract

Extant research has shown that cross-national variations in the level of a country ’s democracy tend to be related to its propensity to be involved in external conflict. The dyadic version of the theory of democratic peace contends that democracies rarely, if ever, fight each other, and it is strongly supported by the available evidence. The monadic version, suggesting that democracies are in general more peaceful regardless of the nature of the other party involved in a relationship, has been less well supported. This article addresses the latter proposition, seeking to explain the variations in war involvement among the established democracies on the basis of major differences in their institutions of governance. Among the various distinctions considered (such as parliamentary versus presidential forms of government, rule by a single dominant party versus a coalition government, and phases of the electoral cycle), a country ’s electoral system turns out to be the most important institutional factor that dampens war involvement. Established democracies with a proportionate - representation system tend to have significantly less such involvement according to three alternative measures. We adduce insights from comparative studies of democratic politics to explain this major finding, thereby offering a more specific and cogent account of why this particular institutional arrangement matters for external belligerence.