In a time of war, everybody makes proportionality arguments. But proportionality is a fool’s game, more suited to propaganda than to reasoned judgement. Some number of people are killed in some military action: are the deaths proportional? How might we know? The numbers are always disputed, and so is the balance of fighters and civilians. And then comes the critical question: proportional to what? There are many answers to that question. Choose the one you want, and it is easy to defend whatever your side is doing or to accuse the other side of committing war crimes.
One answer can be ruled out: our actions are proportional to what the enemy just did to us, as if war is like a feud in old Tennessee. That family killed two of ours, so we will kill two of theirs; three would be a crime. That doesn’t work in international politics or war. So, should we mean proportional to the value of a particular military target? That is the standard required by the Geneva Convention, but it just invites further questions: what contribution does destroying this target make to success in the ongoing battle or the longer-term military campaign—or to victory itself? Or to the deterrence of future conflicts? Or to a just peace?
Consider an example, only partly made up. The RAF is planning to bomb a tank factory in Germany in, say, 1942. The factory is located in a working-class neighborhood—it has not been placed there for civilian cover, it was simply built at a time when workers didn’t have cars. The people who estimate such things say that roughly 200 people living nearby will be killed (a low number considering the targeting devices then available). Is that number proportionate? After all, the Germans have 20 other factories making tanks. Is temporarily cutting 1/20 of German tank production worth 200 innocent lives? Some say yes, some say no. But then someone points out that these tanks are going to a Nazi army, which is still triumphant across Europe. If the end is defeating the Nazis, then, suddenly, 1,000 lives, or even 10,000, do not seem disproportionate.
In the past, proportionality arguments have mostly been used to justify “too much” killing. Right now, the argument is being used to condemn whatever killing the IDF is doing in the Gaza war. In these condemnations, it seems clear that “disproportionate” just means any number that horrifies me. The condemnations began when the numbers were much lower than they are today—and the numbers then and now are disputed. Exactly when did they become disproportionate?