…at least potentially.

Lately a bunch of my Facebook friends have been sharing the Slate article Military Strikes Are An Extremely Expensive Way To Help Foreigners, which is too bad because it’s super super wrong. It is wrong both in design and in execution, and it consigns itself to the special hell for people who make a numerical argument without checking any actual numbers.

Here is its argument: the United States is currently considering whether or not to intervene in Syria. Some people say there are humanitarian grounds for this – after all, Syrians are currently under the heel of a repressive regime and trapped in a deadly war. However, if we were true humanitarians, we could just take the cost of intervening in Syria – maybe a few billion dollars – and donate that money to GiveWell, which would save even more lives.

What I mean by “wrong in design” is that saying “this is less effective than GiveWell’s number one top rated efficient charity” is damning by really really faint praise. Tautologically, if you believe GiveWell then everything is less effective than GiveWell’s number one top rated efficient charity. This includes policies that you – and Matt Yglesias – support. For example, he says nice things about publicly subsidized preschools, but spending money on these preschools is less effective than GiveWell’s top-rated charity. The same is true of other nice things you presumably like such as public libraries, food stamps, PBS, et cetera.

So imagine that in the debate over whether to de-fund PBS a few years ago, someone had brought up that PBS is less cost-effective than GiveWell’s top charities, probably even less effective than its top US charities. And then we all patted ourselves on the back for noticing and decided not to renew funding for PBS. What do you think are the chances that all that funding would have ended up in the hands of poor African villagers?

If someone wants to propose a bill that our government can only spend money on the most effective things, starting with the most effective and only moving on to the second most effective once number one has been saturated, I’d be totally in support of that (and I’ve even tried imagining what such a government could look like). In the absence of such a policy, “let’s stop funding PBS since it’s less effective than GiveWell’s top-rated charity” is a terrible idea, and so is abandoning Syria to its fate for the same reason.

A better policy might be “defund things that produce less utility than tax cuts or the typical government policy”, since we can expect the money saved to either be refunded in taxes or to be distributed among other government policies. And this is where it becomes important that the Slate article was also wrong in its execution.

The article focuses on Libya as an example of an intervention which, although “successful”, was apparently “too expensive”. Let’s calculate how expensive it really was.

The US spent about $1 billion on military intervention in Libya (our allies contributed some more, but we can assume that US participation “bought” allied participation).

There’s no good way of calculating how many lives US intervention saved, but the war up to that point had caused 25,000 casualties, and everyone expected the rebels’ final defeat to be something of a bloodbath. Let’s say intervention prevented another 25,000 casualties.

Suppose the average Libyan currently alive can be expected to live 25 more years. We multiply by 0.7 (for reasons to be explained later) and so those 25,000 lives saved = a gain of 437,500 QALYs.

However, intervention did more than save potential casualties. It also freed everyone from the government of Moammar Gaddafi, a ridiculously evil guy who squandered the country’s wealth and raped his populace both figuratively and literally.

How much should this count for? When I tried to elicit conditional utility weights from people, I didn’t have anything that exactly corresponded to Libya, but it seems reasonable to say it was better than North Korea but worse than China, so maybe around 0.6? And that though post-Gaddafi Libya is still poor and conflict-ridden, it’s just a little bit better, so perhaps 0.7?

So if you improve the lives of 6 million people by 0.1 QALYs/year x 25 years, that’s another 15 million QALYs gained, for a total of about 16 million.

If you purchase 15.5 million QALYs for $1 billion, you find you spent about $65 per QALY.

Compare this to the Against Malaria Foundation. The Slate article boasts that “according to The Life You Can Save, handing out these bed nets saves about one life for every $1,865 spent.”

So here $1,865 buys one life = 50 QALYs (we said 25 before, but let’s be generous since most deaths from malaria are children and so will have more lifespan left to save), but in this case we multiply by 0.5 (the weight the survey gave to life in Ethiopia, which is a proxy for the sorts of countries where AMF likely operates) and get about $75.

So if you accept the main premise of the above – that life is ~10% better in Libya after Gaddafi was overthrown – military intervention in Libya was a bit more effective towards humanitarian goals than donations to AMF, buying QALYs for $65 versus $75.

Let’s put these numbers in a broader context than “one is bigger than the other”. In health care, anything that costs less than about $25,000 per QALY is generally considered excellent value. People wax poetic about the amazing cost-effectiveness of preventative health care because it usually comes out to “only” $1000 – $5000 per QALY. These numbers are both mind-bogglingly low.

And in the case of Libya, this may an underestimate, since it doesn’t take into account shortening the war, or spurring foreign investment, or the fact that Gaddafi probably would have become more repressive after the rebellion, or less tangible effects like deterrence of future dictators.

Didn’t I just say that donating to GiveWell’s top charity must tautologically be the best use of money if you trust GiveWell? Yes, but that’s only true for the average person with a marginal dollar to spare. If you happen to be a superpower with an air force of 5,500 planes and several billions of dollars to burn, you have options that GiveWell probably will not have evaluated.

My guess is a perfectly utilitarian US Air Force (now there’s a plot hook!) would probably require its own GiveWell, at least for a while, rather than selling its planes for scrap and donating to the civilian version.

Am I saying that military intervention is always more cost-effective than civilian charity? Certainly not. Military interventions sometimes cause large numbers of deaths, don’t always keep the costs down as effectively as the Libyan operation did, don’t always succeed, and when they do succeed they risk unintended consequences (like replacing a brutal-but-effective dictator with an anarchic power vacuum).

But if we still had InTrade, we could come up with a probability that each of those things would happen, factor them into our calculations, and who knows, it might still be better than giving to Against Malaria Foundation. Or at least better than giving money to Egypt to buy weapons to point at Israel to counteract the money we gave to Israel to buy weapons to point at Egypt – which, let’s face it, is a much more realistic description of where the typical foreign aid dollar goes than Against Malaria Foundation is.

(note that I do not intend this article to assert that intervening in Syria at present is a good idea. I am currently neutral-ish on this point, since the possibility of making the situation much better seems counterbalanced by a good chance of making it much worse. But this should not be taken as a critique of interventions more broadly, let alone a Fully General one.)

Yglesias’ article ends by saying:

Now, before the kill-and-maim-for-the-sake-of-humanity crowd shoots a Tomahawk missile at me, it’s worth conceding up front that none of this amounts to a logically airtight case against blowing up some Syrian infrastructure and killing various Syrian bad guys. It is very possible for a given undertaking to be worth doing without being the optimal policy. But I do think it’s worth interrogating the larger political and ideological construct that says that spending a few billions dollars to help foreigners is a thinkable undertaking if and only if the means of providing assistance is to kill some people and blow some stuff up. The explosives-heavy approach to humanitarianism has a lot of unpredictable side effects, sometimes backfires massively, and offers an extremely poor value proposition. So whatever you think about killing some Syrians this summer, please consider throwing a few dollars in the direction of a cost-effective charity of some kind.

A big “amen!” to all of that except the “extremely poor value proposition” part.