An Interactive Model of the Democratic Peace: Revisiting the Theory with Elastic Measures

Abstract

Democracies do not take up arms against each other. This axiom has attained the status of a mantra in the field of international relations. As previous research has shown, however, the truth of this statement is highly contingent on the definitions of both democracy and conflict. Based on this fact, this project has two aims: one empirical and one theoretical. Empirically, it revises this literature, making three substantial improvements: 1) it uses a more robust and transparent measure of democracy (V-DEM); 2) it does not rely on arbitrary cut points between democratic and non-democratic regimes; and 3) it combines the theoretical perspectives of similarity-based and normative views on the reasons behind the peace among regimes. These methodological improvements allow us to generate a new theory of democratic peace, which complements both similarity-based and institutional arguments. We find robust evidence that the higher a dyad’s level of democracy, and the smaller the difference between the democratic scores of its members (‘democratic spread’), the lower the probability of war (and also militarized interstate disputes, MID) between that pair of states. Thus, not only is the core principle of the democratic peace revealed to be strong enough to withstand different measures of democracy, but it also offers an alternative explanation of conflict.