The determinants of war in international relations

The study of warfare is one of the oldest and most important dynamics of interest for students of politics. This area of research is predominantly − but not exclusively − undertaken within the sub-field of international relations (IR). IR theorists argue that war is the contingent outcome of the interaction among variables operating at three “levels of analysis”: the international level, the domestic level, and the individual level. The international level explores variables that operate exclusively “above” states such as anarchy and the distribution of power. The domestic level explores variables that operate exclusively within states, such as regime type and bureaucratic design. The individual level explores the ways in which individual psychology (i.e. beliefs, culture, personality) contributes to the outbreak of war. We also offer a discussion of new puzzles and challenges in the study of warfare, such as the decline of war hypothesis and the growing prevalence of civil war, insurgency and non-state violence.