AS MY colleague explains, perceptions of "success" in war may or may not reflect reality. This led me to wonder how we might establish objective success in our Libyan adventure. Naturally, we need some standard of evaluation, and generally success is measured relative to a goal or a set of expectations. So it seems that whether or not America is actually successful in Libya, and not merely perceived to be successful, depends on what exactly it is that we are trying to do there. Unfortunately, this is not as clear as it might be.

As I suggested in a prior post, it is easier to sell the public on "humanitarian intervention" than on "regime change", especially when that regime poses no threat to America or its allies. Consequently, it is not unreasonable to suspect that some among those who desire regime change for Libya publicly make a more palatable humanitarian case for war. Now, President Obama's case for intervention has been a humanitarian one, suggesting we should judge America's intervention in Libya by humanitarian standards. However, as Mr Obama said yesterday in Santiago, "It is US policy that Qaddafi needs to go." Assuming that Mr Obama is, as he says, moved by humanitarian concern, it would seem he is convinced that his stated humanitarian goals cannot be achieved unless Mr Qaddafi's regime falls. This conviction, once expressed, strongly encourages the media and public to judge success or failure in Libya according to whether Mr Qaddafi holds or loses power. Nevertheless, the stated aim of allied attacks on Libyan targets remains humanitarian, and thus it is incumbent upon us to remain dogged in our insistence on the rigorous application of humanitarian standards of success.

Have you heard a persuasive case that Mr Qaddafi's ouster is necessary to achieve our humanitarian aim? I haven't. In order to make this case, one would have to take seriously the goals of reducing death and suffering, and it is by no means clear that these goals would be better met by deposing Mr Qaddafi than by, say, achieving and enforcing an immediate ceasefire that leaves Mr Qaddafi in power.

That none of us can peer through a magical window and witness the counterfactual world in which there is no attempt to topple Qaddafi, or in which there is no allied intervention in Libya, is to the decided advantage of those arguing the humanitarian necessity of our present course of action. Had we done nothing, we would have seen carnage and we would have been told that we could have prevented it. If we see carnage now and in the near future, we will be told that had we done nothing, it would have been even worse. Our cognitive clumsiness with counterfactual scenarios combined with our patriotic wish to see our state as a force for good leaves us ready to believe that yes, surely it would have been even worse had we not acted, or had we acted differently. And this buys interventionists a good deal of time to catch and capitalise on a break that creates the perception of success. The force of the "it would have been even worse" argument will dissipate only if Libya's civil war drags on and the public comes to see our intervention as having helped it drag on. But if the peace is restored before that day, and it probably will, most of us will judge our involvement a humanitarian success, even if, as a matter of perception-independent fact, it turns out not to have been. In that unhappy event, we'll be glad not to know that had we pursued a different policy, fewer people would have needlessly died.

Nevertheless, despite our natural biases, it remains both possible and necessary to intelligently estimate how much suffering and death we can expect intervention to avoid. When opponents of intervention ask us to consider, for example, how many lives could be saved were we to spend the cost of a military mission on anti-malarial bed nets, I understand them to be insisting that we take the stated humanitarian justification for this intervention seriously. If our foreign policy aims to prevent suffering and death with finite resources, it makes sense to ask whether this war makes sense on those grounds. I grasp the tiresome point that the choice on the table was not a choice between taking out Libya's air defences and buying bed nets. The choice was between taking out Libya's air defences or not. But the question nagging some of us is why this was the choice on the table. Why did this come up as a matter requiring urgent attention and immediate decision? Why is it that the choice to express our humanitarian benevolence through the use of missiles and jets gets on the table—to the top of the agenda, even—again and again, but the choice to express it less truculently so rarely does? If our humanitarian values really set the agenda, how likely is it that the prospect of urgent military intervention would come up so often?

It's important that we take the logic of humanitarian justification seriously, but it's true that talk of bed nets tries to do this in a somewhat confused and confusing way. What we really need is intelligent insight into the death and suffering intervention in Libya can be expected to prevent relative to other feasible options. That no one seems even to try to do this in a serious or systematic way—that it seems almost surprising when someone notes the existence of options "between sitting on our hands and launching something close to all-out war"—suggests that objective humanitarian success isn't actually the guiding light of Operation Odyssey Dawn.