At Crooked Timber:

“The absence of war between major established democracies is as close to anything we know to a simple empirical regularity in relations between peoples.”

John Rawls, The Law of Peoples, pp. 52—3.

Well, obviously it depends on how much you pack into “major” and “established”, but, since both Russia and Georgia rate as 7, “fully democratic” on the Polity index, there’s at least some case for saying that there’s just been an exception to that lawlike generalization.[fn1]