Mainstream moral beliefs about war seem to be inconsistent with mainstream moral beliefs about self-defense such as the imminence requirement, the requirement to retreat, and restrictions on responses to conditional threats. The chapter argues that these apparent inconsistencies are actually the result of the necessity principle applied to environments with different nonmoral social facts. War takes place in the anarchy of international relations, where a lack of effective cosmopolitan security institutions makes it necessary to confront nonimminent threats, stand one’s ground, (...) and respond to conditional threats in order to defeat and deter aggression. Self-defense, on the other hand, usually occurs in societies with effective police. In such an environment, it is unnecessary for private citizens to take similar actions to defeat and deter aggression. This is a good reason to believe that mainstream moral beliefs about war are closer to the true morality of war than recent critics claim. (shrink)