Just War theory—and its principles and doctrine—has for many centuries represented the pinnacle of human morality in warfare. As such, it has informed and influenced the formulation of international laws and treaties in the protection of non-combatants, civilians, and vulnerable categories of individuals.

The most important intellectual work examining the application of just war principles to modern wars remains Michael Walzer’s Just and Unjust Wars (1977), a classic investigation into just war doctrine applied within the context of inter-state war and civil conflict during the Cold War. Yet, no volume since the end of the Cold War has successfully become the successor to Walzer’s book.

This failure is certainly not due to a lack of research and writing about ethics and war. Indeed, there are lively and ongoing debates concerning just war doctrine in a number of academic disciplines and among policymakers and policy analysts. These groups, however, rarely speak to each other and there is a growing gap between strong scholarship regarding ethics and war and policy-relevant work that can influence government decisions and public debates. Trends in universities, which increasingly prioritize analytic philosophy in philosophy departments, formal models and game theory in political science departments, and social history over military history in history departments, have all contributed to the relative neglect of the study of the evolution of just war doctrine and applications to real world security problems.