Subjective proportionality

Philosophers writing about proportionality in self-defense and war will often assume that defensive agents have full knowledge about the threat that they face and the defensive options available to them. But no actual defensive agents possess this kind of knowledge. How, then, should we make proportionality decisions under uncertainty? The natural answer is that we should move from comparing the harm we will do with the good we will achieve to comparing expected harm with expected good. I argue that this simple calculation is flawed, and I begin to develop a more sophisticated account of “subjective proportionality.