One of features of recent discussions of when military force can justly be used is a suspicion about the traditional distinction between questions about the justice of the resort to force and the justice of individual uses of force. This distinction between the jus in bello and the jus ad bellum is at the heart of the doctrine, apparently central to the law of war, of the moral equality of combatants. This holds that the justice of cause that combatants fight is irrelevant for assessments of the justice of their actions. One work which has argued that combatants are not morally equal is David Rodin's War and Self-Defense. Rodin, however, uses rather a suspect argument to cast doubt on the distinction. He insists that it is paradoxical if
the war taken as a whole is a crime, yet that each of the individual acts which together constitute the aggressive war are entirely lawful
Perhaps Rodin thinks that every part of a car must have the same properties as the car itself. If nothing else, seeing him trying to drive a door handle home should be amusing. Nor is this a point which political and moral philosophy is unaware of. The dangers of fallacies of composition are an important part of Jerry Cohen's arguments against libertarianism in his Self-Ownership, Freedom and Equality, for example, quite apart from their role in the arguments of the later Rawls for the special significance of basic political, social and economic institutions over and above the acts that make them up. Nor is this the only lacuna in Rodin's book: for example, it seems to be a premise in his account of why legitimacy cannot ground state's rights to defend themselves that if a state has the right to rule over its own population, it must have the right to rule over everyone else as well. I recently read an interview with Michael Walzer (here) in which he was quite bitter about the reception the profession gave to his two major works, and in particular to his work in just war theory, Just and Unjust Wars, which is explicitly one of Rodin's targets. It's not always easy to be sympathetic to Walzer, but Rodin manages to make it seem so.
In terms of the discipline, one of the interesting things about the pattern of Rodin's mistakes is that although I disagree with his account of individual rights of self-defence, it is powerful in a way that his account of the rights of collectives is not. Applied moral philosophy, anyone?