Structural Realism after the Cold War

Structural Realism after the Cold War Kenneth N. Waltz Some students of international politics believe that realism is obsolete.1 They argue that, although realism’s concepts of anarchy, self-help, and power balancing may have been appropriate to a bygone era, they have been displaced by changed conditions and eclipsed by better ideas. New times call for new thinking. Changing conditions require revised theories or entirely different ones. True, if the conditions that a theory contemplated have changed, the theory no longer applies. But what sorts of changes would alter the international political system so profoundly that old ways of thinking would no longer be relevant? Changes of the system would do it; changes in the system would not. Within-system changes take place all the time, some important, some not. Big changes in the means of transportation, communication, and war ªghting, for example, strongly affect how states and other agents interact. Such changes occur at the unit level. In modern history, or perhaps in all of history, the introduction of nuclear weaponry was the greatest of such changes. Yet in the nuclear era, international politics remains a self-help arena. Nuclear weapons decisively change how some states provide for their own and possibly for others’ security; but nuclear weapons have not altered the anarchic structure of the international political system. Changes in the structure of the system are distinct from changes at the unit level. Thus, changes in polarity also affect how states provide for their security. Signiªcant changes take place when the number of great powers reduces to two or one. With more than two, states rely for their security both on their Kenneth N. Waltz, former Ford Professor of Political Science at the University of California, Berkeley, is a Research Associate of the Institute of War and Peace Studies and Adjunct Professor at Columbia University. I am indebted to Karen Adams and Robert Rauchhaus for help on this article from its conception to its completion. For insightful and constructive criticisms I wish to thank Robert Art, Richard Betts, Barbara Farnham, Anne Fox, Robert Jervis, Warner Schilling, and Mark Sheetz. 1. For example, Richard Ned Lebow, “The Long Peace, the End of the Cold War, and the Failure of Realism,” International Organization, Vol. 48, No. 2 (Spring 1994), pp. 249–277; Jeffrey W. Legro and Andrew Moravcsik, “Is Anybody Still a Realist?” International Security, Vol. 24, No. 2 (Fall 1999), pp. 5–55; Bruce Russett, Grasping the Democratic Peace: Principles for a Post–Cold War Peace (Princeton, N.J.: Princeton University Press, 1993); Paul Schroeder, “Historical Reality vs. Neorealist Theory,” International Security, Vol. 19, No. 1 (Summer 1994), pp. 108–148; and John A. Vasquez, “The Realist Paradigm and Degenerative vs. Progressive Research Programs: An Appraisal of Neotraditional Research on Waltz’s Balancing Proposition,” American Political Science Review, Vol. 91, No. 4 (December 1997), pp. 899–912. International Security, Vol. 25, No. 1 (Summer 2000), pp. 5–41© 2000 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. 5 own internal efforts and on alliances they may make with others. Competition in multipolar systems is more complicated than competition in bipolar ones because uncertainties about the comparative capabilities of states multiply as numbers grow, and because estimates of the cohesiveness and strength of coalitions are hard to make. Both changes of weaponry and changes of polarity were big ones with ramiªcations that spread through the system, yet they did not transform it. If the system were transformed, international politics would no longer be international politics, and the past would no longer serve as a guide to the future. We would begin to call international politics by another name, as some do. The terms “world politics” or “global politics,” for example, suggest that politics among self-interested states concerned with their security has been replaced by some other kind of politics or perhaps by no politics at all. What changes, one may wonder, would turn international politics into something distinctly different? The answer commonly given is that international politics is being transformed and realism is being rendered obsolete as democracy extends its sway, as interdependence tightens its grip, and as institutions...