There are many arguments to condemn the Israeli response to Hamas, but disproportionality, as measured by lives lost, should not be one of them. Ezra Klein has made the argument this way: "There is nothing proportionate" in a conflict that kills 280 Palestinians and only a few Israelis. Matt Yglesias has expanded on this, insisting that reasoning about intentions is all well and good, but "at some point you need to judge based on what's actually happening, and what's happening is that whatever Hamas' ambitions [are], they were... causing little damage." Israel's actions are, because of this, "unreasonable."
This argument, however, holds little water. War is terrible, but it is also complicated, and its legitimacy cannot be judged by a simple death tally. There are other questions that weigh in. For example, one of Israel's goals in attacking Hamas is to impair the supply chain that transports smuggled arms. Should they succeed, how many future deaths would be prevented? Or, if Israel does not invade Gaza, how many more lives will it embolden Hamas to kill? Continuing with this macabre arithmetic, say we could measure these hypothetical gains, is it "proportional" when 280 Israeli lives are saved, or does it just have to be a ballpark figure? These are necessarily subjective questions of great moral complexity, and the false standard of "proportionality" evades tough issues.
There is something else that is morally evasive about the proportionality argument. I wonder whether Americans who criticize Israel would ever subject the United States to "a proportional war." The first Gulf War saw anywhere from 1000 to 3000 civilian Iraqi deaths compared to the U.S. non-combat deaths 7 to 20 times less. Clearly disproportionate, but that did not ruin the effort for most people. Jon Chait also brought to light the U.S. response to Japan in World War II, where the U.S. intentionally killed more Japanese civilians than vice versa. Confronted with the untidiness of history, what does it even mean to have a proportionate response?
Matt Yglesias and Ezra Klein are reasonable people. What I'd be interested to know is how they would advise Israel. Would they suggest doing nothing, to-- contra Barack Obama--let rockets and mortar shower the families of cities like Sderot and Ashkelon? Or would they match an eye for an eye, to launch the same number of rockets that Hamas launches? Or might they pursue a third option, to escalate and to increase the costs to Hamas for attacking Israel? This is what is happening now, and in the best-case scenario, it restores an element of deterrence to Hamas' decision-making calculus, increasing the costs of violence in order to decrease its future likelihood. If Hamas is rational, as I think it is, it will respond accordingly. Either way, I do not see a more reasonable alternative.