Perspectives on Psychological Science, Ahead of Print.
What is judged as morally right and wrong in war? I argue that despite many decades of research on moral psychology and the psychology of intergroup conflict, social psychology does not yet have a good answer to this question. However, it is a question of great importance because its answer has implications for decision-making in war, public policy, and international law. I therefore suggest a new way for psychology researchers to study the morality of war that combines the strengths of philosophical just-war theory with experimental techniques and theories developed for the psychological study of morality more generally. This novel approach has already begun to elucidate the moral judgments third-party observers make in war, and I demonstrate that these early findings have important implications for moral psychology, just-war theory, and the understanding of the morality of war.