Jonah, the good thing about democracies is that ‘rule by expert’ is not how they are run. If 85% of Americans think that the US should intervene under those circumstances that seems like a pretty clear expression of the popular will (and, as we both agree, the popular will is relevant in helping us come to a definition of the national interest) and I can see no objection to it. And, yes, it would also (in my view) be the right thing to do.