Prior to the Iraq War, the war in Libya, and any intervention we may or may not undertake in Syria, some hawks insistently argue(d) that there is a humanitarian imperative to step into the breach.
Their arguments can be powerful.
Innocent people are dying at the hands of a tyrant. We have the most powerful military on earth. If we do nothing, the slaughter will continue. And don't most of us agree that some military interventions, like the one that stopped the Holocaust, would've been justified on purely humanitarian grounds, even if stopping the death camps wasn't the rationale for WWII at the time?
There are many non-interventionist counterarguments. One is that even in situations where death is guaranteed absent intervention, it is still possible to unwittingly make a terrible situation worse.
Another is that war is very costly in U.S. lives and treasure.
And isn't it unfair to order people who joined the military to defend their country to risk their lives for a different cause, however noble?
While open to interventions in the most extreme cases, I'm generally a non-interventionist, and although there are several reasons I feel that way, one in particular seems to be missing from the national debate: Almost every time someone calls for a war to be entered on humanitarian grounds, there's a way to save more lives more cheaply and reliably with philanthropic spending.
(They are often, to be sure, different lives.)
International development is itself a complicated subject. Well-intentioned efforts often fail and sometimes unintended consequences do harm. But compared to a war gone wrong like Vietnam or Iraq, the downside risk is much lower, and success doesn't require any Americans to come home in caskets or any foreigners to be killed. Against Malaria Foundation, one of the most efficient little charities out there, is really good at saving lives with mosquito nets. Or take this passage from the interview that Ezra Klein has just done with Bill Gates about his charity work:
EK: What's been the biggest surprise? What has the data shown works, or doesn't work, that you simply didn't expect?
BG: I was completely surprised that nobody was funding some of these vaccines. When I first looked at this I thought, well, all the good stuff will have been done. It was mind-blowing me to find things like Rotavirus vaccine were going unfunded. One hundred percent of rich kids were getting it and no poor kids were. So over a quarter million kids a year were dying of Rotavirus-caused diarrhea. You could save those lives for $800 per life. That's like $20 or $30 per year of life. It's just ridiculous that an intervention like that isn't funded.
It's easy to think of a hypothetical where a very cheap military intervention could save a lot of lives. Perhaps Rwanda is a genocide that could've been stopped at a price such that no alternative expenditure of the same resources could've saved more lives. Perhaps we should've stopped it.
But a situation like Syria?
A humanitarian call to intervene there by putting weapons in the hand of one faction or American boots on the ground has a hefty price-tag in dollars alone, huge downside risk, and unpredictable consequences. And even if it's true that doing nothing will result in sure death for many, the same is true if we do nothing about disease or sanitation or infrastructure or working conditions in much of the developing world. That isn't an argument for doing nothing. It's an argument for directing whatever we decide is the right amount to spend on humanitarian causes in a way that maximizes the utility of every dollar. When an interventionist wants to put boots on the ground, arguing that it's necessary to save lives, it means asking ourselves, before acceding, "can more lives be saved by spending this money on anything other than a war"? The fact is that, even granting the smartest critiques of international development work, it is usually a better way to help people than war, and it engenders good feelings rather than blowback.