The literature on international hierarchy is emerging as a progressive research program. This new theory of international relations is generating novel propositions that are being empirically confirmed. Some propositions, like the hierarchical peace, provide new explanations for previously identified phenomena. Other propositions on defense spending, crisis joining,e trade, and civil wars and repression establish new empirical relationships that—if they are not actually inconsistent with existing theories—were not previously identified. If the measure of progress is the uncovering of new facts, the new hierarchy studies are clearly moving in the right direction. Further progress requires more and better measures of hierarchy and continued testing of propositions derived from the theory.
Joachim K. Rennstich
Multilevel governance (MLG) as a research approach has mostly been applied to explain governance issues surrounding the European Union or international organizations. As a general research framework in the area of international relations (IR) theory, however, MLG has widely been underutilized, despite the many advantages that the approach offers in the empirical investigation of an increasingly complex international or global system. There are key concepts, assumptions, and definitions of MLG that focus separately on levels and governance as key elements of the approach and its interdisciplinary lineage. Some contested IR concepts include sovereignty, the nation-state, the international system, anarchy, agency, and levels of analysis. These IR concepts benefit from the application of an MLG framework by enabling the use of an interdisciplinary and multimethodological, yet systematically comprehensive, approach—which allows for nuanced use of these concepts. Other areas that benefit from IR methodologies applied in MLG research are methodological toolkits with a special focus on the areas of global governance, security studies, and international political economy.