The debate over going to war in Iraq has in many quarters become a debate about the ethical implications of preemption and prevention rather than about the war itself. But neither prevention nor preemption can have any moral standing in the abstract, since it is the circumstances, not the concepts, that inform their qualities as strategies. The question, rather, is whether the decision to engage in a new war against the Iraqi regime is just.

Indeed, it is surprising to find that so much less has been said about basic principles of just war—that is, a just cause, a right intention, proportionality, and so on—than about the largely legal questions of preemption and prevention. But concepts like preemption and prevention are really about the timing and method of war; they say nothing about the moral content of the conflict itself, and in the end an emphasis on them obscures the fundamental question of justice. Put another way, if a particular military action, including launching war, is just and proper, then the means and scheduling are subject, like anything else, to scrutiny under the guidance of the principles of just war. But they are not separate questions in and of themselves.