Permanent Friends? Dynamic Difference and the Democratic Peace


  • The authors thank participants at seminars at the University of California, Los Angeles, the Texas A&M University, and the Swiss Federal Institute of Technology (ETH) for their comments. An earlier version of this paper was presented at the Midwest Political Science Association, April 12–15, 2007, Chicago, IL, where it was awarded “Best IR paper.” Data, a STATA "do” file, and code for the theoretical model will be available upon publication.


Perhaps the simplest explanation for where fault lines lie in a political process involves the presence of an "other." Difference divides and similarity unites. These similarities and differences can in turn orient and propagate conflict. Yet, similarity and difference are also dynamic, evolving in response to changing population characteristics or a new reference point. We offer a simple explanation for interstate conflict in which the salience of similarity or difference varies with the prevalence or capabilities of groups. We apply our argument in the context of the democratic peace. When democracies are scarce or weak, and autocracies plentiful and powerful, democracies face a common threat. As the democratic community strengthens, however, the threat from autocracies declines and differences among democracies appear more salient. Our findings contrast with standard expectations about how democratization shapes world affairs.