Like most residents of New England, I've spent the past day digging out from a major snowstorm. Unlike most of my neighbors, I've also spent many hours grading the take-home final from my course. It occurred to me that some of you might like to know what we asked our students, and what some of them had to say about it.

The exam was in two parts, and the first part consisted of the following hypothetical question:

 Q1: "Due to an unexpected movement of tectonic plates, the United States and China have switched geographic locations. The United States is now located in East Asia; sharing borders with Russia, North Korea, India, Mongolia, Vietnam, etc., and is much closer to Japan, while China is now located in North America, in-between Canada and Mexico. Assume that all other features of the two societies are unchanged (i.e., each state faces this new situation with the same populations they have today, along with the same natural resource endowments, military capabilities, economic systems, political institutions, etc.).

 The question: how would this development affect contemporary international relations? Your answer should draw upon the theoretical material covered in this course (e.g., realism, liberalism, constructivism, etc.) but feel free to add your own ideas as well."

Students were given 1250 words (5-6 pages) to address this question, and most of them did pretty well with it. The question is obviously designed to get them to think through what different theories tell you about how geography would affect relations between states. For instance: would US relations with India and Japan deteriorate if the US were located nearby, or would shared democratic values dampen potential rivalries? Would China try to establish regional hegemony in the Western hemisphere, and would states like Canada, Mexico or Brazil try to contain it? Or would they "bandwagon" with China as they have done with the United States? Would the United States have to curtail its global ambitions in order to deal with security problems closer to home -- such as Pakistan, North Korea, Burma, or Russia -- or would it feel compelled to use force against a threatening neighbor like North Korea? There's no single "right answer" to this sort of question; what I'm looking for is a clear, logically consistent, and well-argued set of predictions.

Not surprisingly, many of the papers argued that switching places would be a tremendous benefit to China. In particular, students clearly recognized that the United States enjoys some enormous geographic advantages. In addition to being wealthier and more powerful than any of the other major powers, the United States is protected by two enormous oceanic moats and has no great powers in its immediate neighborhood. Moving from East Asia to the Western hemisphere would put China in this same favorable position, and place the United States in a much more problematic location in East Asia.

But what was really interesting was an implication that some (though hardly all) students drew from this line of argument. A number of them argued that China would be so secure in the Western hemisphere that it could focus even more attention on economic development, and not worry very much about military or security developments elsewhere. It would want to defend its own territory, and it would worry about securing energy supplies from Canada, Venezuela, Mexico, and elsewhere, but otherwise it would be sitting pretty and could remain aloof from lots of other security issues. The United States, by contrast, would be facing all sorts of challenges over in Asia and would have to try to deal with all of them.

An obvious question, therefore, is: why doesn't this same logic apply to the United States today? Instead of devoting trillions of dollars to transforming the Middle East, trying to bring Afghanistan into the 20th century (or is it the 19th?) and generally interfering all over the world, the United States could almost certainly do a lot less on the world stage and devote some of those resources to balancing budgets and fixing things here at home. It's called nation-building, but we'd be building our nation and our future, not somebody else's.

What some of our students have intuitively grasped (and not because we told them), is that there is in fact a very powerful case for a much more limited U.S. military posture overseas. Indeed, given the existence of nuclear weapons, there is even a cogent case to be made for something approaching isolationism, as laid out by people like the late Eric Nordlinger, by the CATO Institute's Chris Preble, or the team of Gholz, Press, and Sapolsky. I don't go quite that far myself (i.e., I'm an offshore balancer, not an isolationist), but I recognize that there is a serious case for the latter position. And because this view does have a certain appeal, the current foreign-policy establishment has to do a lot of threat-mongering and engage in a lot of ideological oversell in order to get Americans to keep paying for foreign wars and sending their sons and daughters out to garrison the globe. It also helps to portray anybody who advocates doing less as some sort of idealistic pacifist or naive appeaser.

But this debate is beginning to open up. When states and local governments are facing bankruptcy, when military adventures like Iraq or Afghanistan yield not victory but at best only prolonged and costly draws, and when there is in fact no ideologically motivated great power adversary out there trying to "bury us," then continuing to try to manage the whole goddamn planet isn't just foolish, it's unconscionable. It will probably take another decade for this reality to work its way through our hidebound national-security establishment, but the winds of change are already apparent. And not a moment too soon.

I first saw the Berlin Wall in March 1976, when I arrived for a semester's study at Stanford's overseas program there. As an international relations major interested in security affairs, I wanted to see the Cold War "up close and personal," and what better place to do it than the divided city that was the site of numerous Soviet-American confrontations?

It was an education, especially for a rather naive kid from California who had never been outside the United States. Foreigners could visit East Berlin relatively easily by then, yet crossing at Checkpoint Charlie was always a somewhat forbidding experience. The lines to cross were often long and tedious, the border guards sullen and arbitrary, and I always seemed to be the person they wanted to take into the back room for an extra search and a lot of questions.

The Wall itself was an ugly thing: a concrete scar across a once-great city, complete with barbed wire, guard towers, and checkpoints. It was both an iconic symbol of division but also something very real and tangible. It divided families, stifled dreams, and sometimes killed people. Some 5,000 people reportedly tried to get across the Wall while it stood, and a hundred or more died in the attempt.

Like other barriers that divide human beings, the Wall was also a confession of failure. Had the communist vision been a success, there would have been no need for Wall to keep people in. It was an education in itself to live in West Berlin and to visit the East; whatever the failings of liberal capitalism might be, it was palpably superior to life on the Other Side. West Berlin seemed a bit like Oz -- a vibrant, lively, and decidedly materialistic city, filled with cafes, stores, students, dogs (and a lot of elderly people too), but East Berlin was a bit like Dorothy's black-and-white Kansas: drab, monochromatic, and obviously much poorer. And by most accounts, East Germany worked better than the rest of the Soviet empire did.

What lessons do I draw from the Wall, its history, and its eventual destruction? Here are five.

First, although the Wall was an affront to human freedom, it also made a signal contribution to global stability. Berlin had been a flash point for international politics in 1948, 1958, and again in 1961, largely because Germany's fate remained uncertain so long as the DDR continued to lose people to the economic miracle in the West. As Marc Trachtenberg pointed out some years ago, the erection of the Wall completed the Cold War division of Europe and dampened security competition there significantly.

The second lesson is that containment worked. The Wall eventually came down because the Soviet Union collapsed without a superpower war, and Eastern Europe was liberated peacefully. As Kennan had foreseen, the Western system was in fact superior to the communist order on numerous dimensions, which meant that patient forbearance made more sense than a strategy of "rollback" or preventive war. We might have brought the wall down sooner by starting a big war, but fortunately leaders on both sides understood how foolish that would have been. There's a lesson there for those trigger-happy folks who think preventive action is the best way to deal with threats, even dangers that far less ominous than the Soviet Union was.

Third, if containment worked, the fall of the Berlin Wall was a vivid reminder that empires don't. The history of the 20th century is littered with the corpses of the Ottoman, Russian, Austro-Hungarian, British, French, Dutch, and Soviet empires -- none of whom could withstand the corrosive solvent of modern nationalism. Once the desire for national self-determination had the opportunity to express itself, the Soviet empire collapsed with remarkable swiftness.

Fourth, the destruction of the Wall-and indeed, the collapse of the entire Soviet order-teaches that revolutionary upheavals are nearly impossible to forecast with any precision. As Timur Kuran and others have shown, an individual's willingness to rebel is a form of private information that cannot be reliably known in advance, especially in an authoritarian society where repression is a real possibility. As a result, seemingly minor events can suddenly induce rapid contagion effects that even the participants themselves did not anticipate. Although a few observers recognized that the Soviet order was in trouble, hardly anyone believed it could collapse as quickly as it did or that Germany would reunify in a few years. The real lesson, however, is that although dramatic political change does occur from time to time, it rarely does so accordingly to anyone's timetable. The moral: Don't base your policy towards an adversary on the assumption that its rulers are on their last legs. Maybe they are, but maybe not, and nobody really knows.

Fifth and last, the fall of the Wall highlights the critical role of the individual in history. I'm a big believer in the importance of large structural forces -- the changing distribution of power, economic growth rates, demographic trends, and even evolving normative understandings -- but history sometimes turns on an individuals's ideas and initiatives. As I see it, it wasn't Reagan's saying "Mr. Gorbachev, tear down this wall" that led to it being broken into a million pieces (and then sold off, in a wonderful symbol of capitalist triumph), it was the fact that Gorbachev listened and was already thinking along similar lines. Had Andropov or Chernenko been younger or in better health, the Wall would have remained standing well into the 1990s, and we would not be celebrating anything today.

So as we congratulate ourselves for winning the Cold War and congratulate Germans on the destruction of a hated symbol of division, let us also reserve a word of thanks for those on the other side who also helped make that destruction possible.

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