Reassessing the Democratic Peace: A Novel Test Based on the Varieties of Democracy Data

Abstract

The democratic peace is one of the most robust findings in international relations. Yet it suffers from two important limitations. First, even those who fully embrace the democratic peace have difficulty precisely identifying which facet of democracy drives the result. Second, the vast majority of studies have relied on a single measure of democracy - the Polity index. This paper reassesses interstate conflict on several new measures of democracy and their disaggregated components from the Varieties of Democracy project in a global sample of 173 countries from 1900-2010 (www.v-dem.net). We theorize three distinct mechanisms of constraint that may explain why some countries do not engage in military conflict with each other: formal vertical (e.g. elections), informal vertical (e.g. civil society activism), and horizontal accountability (e.g. interbranch constraint on the executive). We find that the formal vertical channels of accountability provided by elections are not as crucial as horizontal constraint and the informal vertical accountability provided by a strong civil society.