In his recent essay on why America uses force so often, Steve Walt breezily dismisses the notion that the Libyan operation avoided a humanitarian disaster:

As Alan Kuperman of the University of Texas and Stephen Chapman of the Chicago Tribune have now shown, the claim that the United States had to act to prevent Libyan tyrant Muammar al-Qaddafi from slaughtering tens of thousands of innocent civilians in Benghazi does not stand up to even casual scrutiny. Although everyone recognizes that Qaddafi is a brutal ruler, his forces did not conduct deliberate, large-scale massacres in any of the cities he has recaptured, and his violent threats to wreak vengeance on Benghazi were directed at those who continued to resist his rule, not at innocent bystanders. There is no question that Qaddafi is a tyrant with few (if any) redemptive qualities, but the threat of a bloodbath that would "stain the conscience of the world" (as Obama put it) was slight. 

In the columns that Walt cites, Kuperman and Chapman made some interesting arguments casting doubt on claims of an imminent massacre. Kuperman is particularly struck by the absence of footage documenting assaults on civilians:

[Gaddafi's] forces certainly harmed innocents while defeating rebels in urban areas, as U.S. forces have done in Iraq and Afghanistan. And he did threaten "no mercy" in Benghazi, but Gadhafi directed this threat only at rebels to persuade them to flee. Despite ubiquitous cellphone cameras, there are no images of genocidal violence, a claim that smacks of rebel propaganda.

To claim, as Walt does, that these provocative thoughts demonstrate that the chances of a bloodbath were slight is an epic overreach. What's more, their arguments must be set against those of experienced human rights experts, including Human Rights Watch's Tom Malinowski:

[W]e should acknowledge what could be happening in eastern Libya right now had Qaddafi’s forces continued their march. The dozens of burned out tanks, rocket launchers, and missiles bombed at the eleventh hour on the road to Benghazi would have devastated the rebel stronghold if Qaddafi’s forces had been able to unleash them indiscriminately, as they did in other, smaller rebel-held towns, like Zawiyah, Misrata, and Adjabiya. Qaddafi’s long track-record of arresting, torturing, disappearing, and killing his political opponents to maintain control suggests that had he recaptured the east, a similar fate would have awaited those who supported the opposition there. Over a hundred thousand Libyans already fled to Egypt fearing Qaddafi’s assault; hundreds of thousands more could have followed if the east had fallen. The remaining population, and those living in refugee camps abroad, would have felt betrayed by the West, which groups like Al Qaeda would undoubtedly have tried to exploit. Finally, Qaddafi’s victory—alongside Egyptian president Hosni Mubarak’s fall—would have signaled to other authoritarian governments from Syria to Saudi Arabia to China that if you negotiate with protesters you lose, but if you kill them you win.

This is a critical debate to have. If humanitarian intervention is to remain a live possibility, there must be much more public scrutiny, debate and discussion of what triggers that intervention and what level of evidence we can reasonably require. Did administration officials have communications intercepts suggesting plans for large-scale killings of civilians? How exactly did they reach their conclusion that these reprisals were likely? It should be no more acceptable to simply accept government claims on this score than it was for previous administrations.

As I've argued previously, the term "humanitarian crisis" is desperately imprecise and the informed public's ability to distinguish between civil strife (which is always bloody) and outright massacres and extermination campaigns is weak. Walt's certainty notwithstanding, the debate about the humanitarian rationale in this case has not been settled. In fact, it's barely begun.