Haass, the president of the Council on Foreign Relations, argues that “just war theory is too subjective and confining for today’s real-world threats. A more useful concept is that of justifiable war.” Elaborating that first point, he writes, “One problem with just war theory is that it is too subjective. What constitutes a just cause is in the eyes of the beholder, as are the probability of success and any estimate of likely costs and benefits.” How does “justifiable war” avoid this problem? Whether a war is “justifiable” will also involve subjective judgments, including–as Haass himself suggests–judgments about the likely costs and benefits of military action. Is this subjectivity really a flaw of just-war thinking in the first place? Haass’s critique seems to envision a theory that will receive objective inputs and spit out the right answer on whether to go to war as though it were a computer. He does not supply such a theory because no such theory can be supplied.

Haass adds, “Just war theory is also too confining. Is the United Nations Security Council the only competent authority, or was NATO’s approval enough to make the Kosovo war just? Waging war only as a last resort means risking the lives of many while other policies are tried and found wanting.” Here Haass’s objection seems to be with crude and narrow applications of just-war thinking rather than the underlying tradition. It is certainly not the case that just-war theorists have historically regarded the UN Security Council as the only legitimate authorizer of war, nor is it the case that all just-war theorists today so regard it. The “last resort” criterion, meanwhile, is probably better understood in terms of a mental process of considering alternatives rather than in terms of serially trying different policies. (Competent authorities should not, that is, feel obligated to try policies that they have good reason to think will fail disastrously.)

So it seems to me that Haass has identified a problem that isn’t a problem and devised a solution that isn’t a solution.