Kantian fractionalization predicts the conflict propensity of the international system

The study of complex social and political phenomena with the perspective and methods of network science has proven fruitful in a variety of areas, including applications in political science and more narrowly the field of international relations. We propose a new line of research in the study of international conflict by showing that the multiplex fractionalization of the international system (which we label Kantian fractionalization) is a powerful predictor of the propensity for violent interstate conflict, a key indicator of the system's stability. In so doing, we also demonstrate the first use of multislice modularity for community detection in a multiplex network application. Even after controlling for established system-level conflict indicators, we find that Kantian fractionalization contributes more to model fit for violent interstate conflict than previously established measures. Moreover, evaluating the influence of each of the constituent networks shows that joint democracy plays little, if any, role in predicting system stability, thus challenging a major empirical finding of the international relations literature. Lastly, a series of Granger causal tests shows that the temporal variability of Kantian fractionalization is consistent with a causal relationship with the prevalence of conflict in the international system. This causal relationship has real-world policy implications as changes in Kantian fractionalization could serve as an early warning sign of international instability.Comment: 17 pages + 17 pages designed as supplementary online materia

Coalition Quality and Multinational Dispute Outcomes

Multinational military coalitions are an increasingly common phenomena in international conflict, presumably because coalitions are more likely to secure their conflict aims than single states. Yet what makes a coalition more or less likely to succeed is poorly understood. We argue that the quality of multinational military coalitions—in terms of the coalition’s skill, coordination, and legitimacy—can provide better strategic decisions, more harmonious relations within the coalition, and thus a greater chance of securing conflict aims. Empirical testing reveals that elements of coalition quality do in fact affect the probability of military success: a history of success, both alone and with the same coalition partners, predicts military success. Moreover, increasing a coalition’s legitimacy via more diverse members has a weak effect, indicating that diversity comes at the expense of coordination and cooperation challenges. Last, we find that elements of coalition quality affect initiating and defending coalitions differently