[pmichaud]

In the original essay, "reasonable" specifically meant "rational" in the sense of "able to be deduced from first principles." The point of the whole essay was that math was was spookily good at modelling reality, empirically speaking, but that fact is super weird considering we have no rational basis to expect that to be the case--ie. we have no first principles based in physical reality that we could use to deduce that math/twiddling with the relationship between symbols using rules we basically just made up should be able to model reality the way it does, and isn't that a strange mystery to contemplate.

Most essays that use the phrase really just mean "surprisingly effective," which is a pet peeve of mine, but I think this essay gets a pass because it's trying to actually address that "strange mystery."