SINCE THE demise of Marxism, political realism has come under increas-ing attack from many political liberals. It is almost as if, having defeated their opponents on the left, liberals have now turned their as-

sault rightward to the third most important contender for intellectual hegemony in the arena of international affairs. Liberal thinkers have attacked political realists especially for the latter's refusal to believe that, with the defeat of the Soviet Union and the end of the cold war, the liberal millennium of democracy, unfettered markets, and peace is upon us. Whereas political realists (who have never had much hope for the human species to begin with) are, on the whole, a rather tolerant and forgiving lot, liberals (and of course Marxists) tend to be more intolerant of those ideas that appear to stand in the way of human perfectibility; it would seem that liberals and Marxists cannot easily accept the doctrine of intellectual peaceful coexistence. As my colleague Michael Doyle has wisely observed, while liberal societies may not war with one another, liberals are quite aggressive toward their nonliberal opponents.1 The same liberal intolerance appears to hold in the marketplace of competing ideas.