The Battle of the Lexicons

This commentary on Arthur Ripstein’s Tanner Lectures raises doubts about his main claims about ius ad bellum and ius in bello. It argues, among other things, that his views about “settlement by force” entail pacifism, that the moral justification for defensive war applies equally to a limited range of wars of aggression, that some wars of humanitarian intervention are morally justified even if they constitute aggression, and that Ripstein’s reasons for claiming that aggression is always morally wrong do not support a legal prohibition of aggression but instead presuppose such a prohibition. In opposition to Ripstein’s views about ius in bello, the author argues that it is mistaken to suppose that being “part of the war” is the criterion for determining who may be attacked, that the relevant distinction is not between combatants and civilians but between those who are morally liable to attack (which can include some civilians) and those who are not, and that the rules of ius in bello are not prohibitions that can be obeyed equally by both just and unjust combatants.