Disputes, Democracies, and Dependencies: A Reexamination of the Kantian Peace


Michael D. Ward is professor of political science, University of Washington, Seattle, WA 98195-3530 (mdw@u.washington.edu); Randolph M. Siverson is Distinguished Professor of political science, University of California, Davis, One Shields Avenue, Davis, CA, 95616 (rmsiverson@ucdavis.edu); Xun Cao is a Ph.D. candidate at the University of Washington (xuncao@u.washington.edu); he will be a post-doctoral fellow at the Princeton Center for Globalization and Governance during 2007–2008.


Militarized interstate disputes are widely thought to be less likely among democratic countries that have high levels of trade and extensive participation in international organizations. We reexamine this broad finding of the Kantian peace literature in the context of a model that incorporates the high degree of dependency among countries. Based on in-sample statistical tests, as well as out-of-sample, predictive cross-validation, we find that results frequently cited in the literature are plagued by overfitting and cannot be characterized as identifying the underlying structure through which international conflict is influenced by democracy, trade, and international governmental organizations. We conclude that much of the statistical association typically reported in this literature apparently stems from three components: (1) geographical proximity, (2) dependence among militarized interstate disputes with the same initiator or target, and (3) the higher-order dependencies in these dyadic data. Once these are incorporated, covariates associated with the Kantian peace tripod lose most of their statistical power. We do find that higher levels of joint democracy are associated with lower probabilities of militarized interstate dispute involvement. We find that despite high statistical significance and putative substantive importance, none of the variables representing the Kantian tripod is associated with any substantial degree of predictive power.