Jerry Muller at Foreign Affairs. The summary of his essay:
Americans generally belittle the role of ethnic nationalism in politics. But in fact, it corresponds to some enduring propensities of the human spirit, it is galvanized by modernization, and in one form or another, it will drive global politics for generations to come. Once ethnic nationalism has captured the imagination of groups in a multiethnic society, ethnic disaggregation or partition is often the least bad answer.
It's about healthy nationalism and the problems with the multicultural "ideal" in most places. Read the whole thing.