Joseph Nye is a rarity in the foreign-policy community-he has held serious policymaking positions in government and acquitted himself well. He has also made significant contributions to international-relations theory and is cited widely. A recent poll of IR academics rated Nye's scholarship as having had the most influence on American foreign policy.

Last week Joseph Nye took to the pages of the Washington Post to complain about his own uniqueness. That is to say, he excoriated the policy irrelevance of international-relations scholars:

Not many top-ranked scholars of international relations are going into government, and even fewer return to contribute to academic theory. The 2008 Teaching, Research and International Policy (TRIP) poll, by the Institute for Theory and Practice in International Relations, showed that of the twenty-five scholars rated as producing the most interesting scholarship during the past five years, only three had ever held policy positions (two in the U.S. government and one in the United Nations). The fault for this growing gap lies not with the government but with the academics.

This has prompted a lot of chatter in the academic blogosphere about whether Nye is right and, if so, how to remedy the problem. Putting aside the question of whether academics should serve the state, it is worth asking whether such remedies are practicable. As someone who has aimed for both policy and scholarly relevance, such steps are potentially laudable. For any sociologist of my discipline, however, the prognosis should be gloomy. The plain fact is that the incentive structure for academic international relations is radically different from the world of policymaking.

To borrow from Isaiah Berlin, academic scholars of international relations are rewarded for being hedgehogs-i.e., knowing one big thing. Scholarship is thought to be "interesting" when an academic generates a really big and provocative idea that challenges conventional understandings of big questions about international relations. The incentive structure of the academy also rewards the academic for repeating and rewriting their big idea as often as possible. Are these big ideas right? That's almost beside the point. As long as their progenitors are alive, ideas never die in international-relations theory (when they do die, someone will eventually dust it off and repackage the idea under their name).

Collectively, the field can operate like this because these big ideas can lead to productive debates about the nature of world politics. The effect on individual academics is less salutary. International-relations theory is by and large a solitary enterprise. Success comes from loudly proclaiming the rightness of one's own views and tearing down alternative ideas. The best of the best usually leave the grubby work of empirical testing to others.

Policymakers, by contrast, are rewarded for being foxes-knowing a little bit about a lot of topics. No policymaker works alone, and they don't start with a blank slate. They must entertain the possibility that policies will not be consistent across countries or issues. The constraints of Congress, interest group pressures, and bureaucratic politics require the ability to compromise with rivals, appease policy principals and manage subordinates. With all due respect, few of my colleagues are up to this task.

This does not mean that academic international relations scholars are useless to policymakers. Criticism is a useful exercise, and my colleagues excel at poking holes in other people's ideas. Occasionally, they even generate some useful policy ideas of their own. Expecting them to shepherd these ideas through the foreign policy machine, however, might be a bridge too far.

Daniel W. Drezner is a professor of international politics at the Fletcher School at Tufts University and a senior editor at The National Interest. His next book, Avoiding Trivia: The Role of Strategic Planning in American Foreign Policy, will be published by Brookings Institution Press later this month.