ABSTRACT
War is the most terrifying and destructive form of violence. Any philosophical analysis of war, therefore, must start with a strong presumption against its permissibility. Yet many people share the intuition that some wars are justified. In spite of the recurrent suspicion that war somehow escapes moral evaluation, that when nations fight all bets are off, philosophers have for centuries attempted to explain what can possibly justify this extreme form of human violence. The morality of war is subdivided into two areas. Ius ad bellum consists of the principles under which states are authorized to wage war. Ius in bello consists of the principles that govern lawful combat. This chapter treats them separately, although the two sets of principles are related in complex ways. But we must first see why war has such a special place in international relations.
