Realism and the end of the Cold War.

radically in a short time. Revolutions or civil strife, as well as wars, may exert profound influence not only on scholars but also on the decision-makers they theorize about. Whatever independent variable one wishes to propose as an explanation of these events, it must have somehow varied a lot in a short time in order to account for the change, or else decision-makers must have received information about it unevenly, in concentrated bursts, rather than incrementally. If we accept the proposition that assessments of power and interest may rationally change quickly in certain periods, then such periods possess unique importance for theory. If that is so, it may not be necessary to invoke "intervening" variables, such as norms, regimes, or institutions, to account for the non-linear, concentrated nature of international change.(81) And it may be misleading to exclude periods of revolutionary Modern realism began as a reaction to the breakdown of the post-World War I international order in the 1930s. The collapse of great-power cooperation after World War II helped establish it as the dominant approach to the theory and practice of international politics in the United States. During the Cold War, efforts to displace realism from its dominant position were repeatedly thwarted by the continued salience of the U.S.-Soviet antagonism: although indirect, the connection between events and theory was undeniable.

Now, the U.S.-Soviet antagonism is history. Suddenly, unexpectedly, and with hardly a shot fired in anger, Russian power has been withdrawn from the Elbe to the Eurasian steppe. A central question faces students and practitioners of international politics. Do the rapid decline and comparatively peaceful collapse of the Soviet state, and with it the entire postwar international order, discredit the realist approach?

Scholars have answered this question in two ways. Most argue that the events of the late 1980s and early 1990s utterly confound realism's expectations, and call into question its relevance for understanding the post-Cold War world.(1) Others - realist and non-realist alike disagree, maintaining that the post-1989 transformation of international politics is not an appropriate test for theory. The end of the Cold War, they argue, was "merely a single data point." Even if it is inconsistent with realism it is insufficient to falsify it, because international relations theories are capable only of predicting patterns of behavior; they cannot make point predictions. And many scholars are pessimistic about the capacity of social science theory to explain unique and complex historical events involving revolutionary change. Therefore, our evaluation of theory should look to future patterns rather than past events.(2)

Both answers are wrong. Realist theories are not invalidated by the post-1989 transformation of world politics. Indeed, they explain much of the story. Realism is rich and varied, and cannot be limited just to structural realism, which deals poorly with change.(3) Many criticisms of realism based on the post-1989 system transformation contrast the most parsimonious form of realism, Kenneth Waltz's structural realism, with the richest and most context-specific alternative explanations derived from liberalism, the new institutionalism, or constructivism. This is not a fair or convincing approach to the evaluation of theories.

Instead, a thoroughly realist explanation of the Cold War's end and the relatively peaceful nature of the Soviet Union's decline that relies entirely on the propositions of pre-1989 theory is in many ways superior to rich explanations based on other theoretical traditions. But to carry on as if there are no lessons in this series of events for international relations theory in general and realist theories in particular is as indefensible intellectually as the claim that the post-1989 transformation single-handedly invalidates any and all realist theories. As critics of realism rightly note, the events of the last half-decade highlight the indeterminacy of realist predictions about state behavior. Realist theories can be made more determinate, but only in ex post explanation rather than ex ante prediction. Realist theories are terribly weak. They are too easy to confirm and too hard to falsify. They do not come close to the ideal of scientific theory. Their strength is only evident when they are compared to the alternatives, which suffer from similar or worse indeterminacy but do not possess comparable explanatory power. The proper attitude toward the realist approach, even on the part of its defenders, ought to be reluctant acceptance conditioned on a determination to improve it, or to dispose of it if

something better comes along.

I perform four basic tasks in this article. First, I discuss briefly the intellectual challenge presented by the post-1989 changes in world politics. What exactly should we expect this series of events to tell us about international relations theories? How much should we expect such theories to tell us about these events? This issue surely ought to lie at the center of any assessment of the Soviet collapse, but thus far it has not. Second, I outline the realist explanation of recent change in world politics that I elaborate upon further throughout the article. Third, I examine the many critiques of realism based on the end of the Cold War and the Soviet collapse: (a) predictive failure; (b) lack of correlation between independent and dependent variables; and (c) important patterns of state behavior defying realist expectations and explanations. Finally, I suggest some preliminary lessons that ought to be drawn from the post-1989 experience, and outline their implications for further research.

The Cold War's End and Social Science Theory

Like the French Revolution or the decline and fall of Rome, the Cold War's end is an event whose importance commands attention but whose complexity frustrates explanation. Few who took up the study of international politics during the Cold War will be content with the notion that the waning of that conflict is simply a single observation no more important than hundreds of others.

And like other complex events in history, the end of the Cold War is unique. The precise set of antecedent conditions and the precise nature of the outcome never occurred before and are exceedingly unlikely ever to recur. So the case cannot be explained in the ideal-scientific manner, as an instance of a general law. That is, the Cold War's end cannot easily be characterized as a type of outcome generally associated with a particular set of antecedent conditions: "Given such-and-such conditions, international systems tend to be transformed; since those conditions obtained in 1987, the Cold War ended as a result."(4) There are simply too many important novel elements in the Cold War story and too few other events even roughly comparable for an explanation of this type to work.

However, if we concentrate on the event itself, we face the familiar problem of too many variables and too few independent observations. International relations theories are almost never monocausal. The claim is rarely "A, not B, caused E," but rather "both A and B caused E but A was more important."(5) Establishing whether nuclear weapons, the balance of power, domestic politics, liberal values, the personalities of leaders, or other factors were truly "most important" in bringing the Cold War to an end is a predictably inconclusive business. In the language of statistics, the researcher faces negative degrees of freedom. If we accept the statistician's view of causality, causal inference cannot be made on the basis of negative degrees of freedom, so the causes of a single outcome cannot be established, and a single outcome will be compatible with numerous theories.(6)

The problem is clear: weak theories that at best can make probabilistic predictions confront a single, complex, but fatefully important event. The solution is twofold. First, it is necessary to disaggregate the event.(7) Elements of the larger event may be susceptible to general explanation. Different theories may explain different regularities that came together to produce the end of the Cold War. At the very least, disaggregation simplifies analysis and clarifies the dependent variable. Second, having selected a piece of the puzzle whose explanation may fall under the purview of a given theory, it is still necessary to go "beyond correlations," in David Dessler's phrase, and toward "a direct examination of a theory's postulated generative processes."(8) The only way to evaluate theory in each instance is to trace the process through which the posited cause produced (or influenced) the outcome. Having posited a cause, and shown a correlation, it will still be necessary to show empirically the mechanism that connects cause to effect.(9)

For the purposes of international theory, it is reasonable to separate the great-power element of the whole case: dramatic change in Soviet security policy; the emergence of a deep detente between the superpowers after 1987; Moscow's peaceful acquiescence in regime changes in East-Central Europe, and the subsequent collapse of its alliance and the reunification of Germany in 1989 and 1990. These events do not constitute the entire story, but they are an important part of it that is particularly relevant to international relations theory. Realist theories of all stripes highlight a single independent variable: the balance of power. They describe recent international change primarily as the result of declining relative Soviet power conditioned by the global distribution of power. For the purpose of evaluating realism, then, much post-1987 international change can be defined as a single series of events, linked by a single generative cause. A causal analysis of that link implies close examination of the influence of power on great-power decision-making during the Cold War endgame.

Strictly speaking, no particular finding about the Cold War's end will suffice to "falsify" an entire research program, such as realism. For a single series of events to constitute a critical test of a theory, it must not only be inconsistent with the theory but be unambiguously ruled out by it.(10) However it may appear to critics of realism, realist theories do not rule out an event-series involving the emergence of deep superpower detente and the relatively peaceful contraction of Soviet power. But the importance of the exercise goes beyond formal arguments about theory-testing. If realism can be shown to have nothing to say about the Cold War's end, its relevance to the postwar world can be called into doubt. And a rigorous search for the causal mechanisms at work in important cases adds to our historical understanding. The clash of theories over the explanation of important events leads to a better understanding of those events.

An Outline of a Realist Explanation

Recent changes in world politics can be explained by realist hypotheses, derived from classical realism and from theories of hegemonic rivalry and power-transition, which have been obscured in recent years by the more influential structural variant.(11) The account I offer is simply an extension of the general realist system of explanation to a specific case with inevitably unique features that could not be anticipated and probably will not recur. Its power derives from the fact that it captures central causal relationships and is connected to a set of theories that have proven their utility in a great many different instances.

The Cold War was caused by the rise of Soviet power and the fear this caused in the West. The end of the Cold War was caused by the relative decline in Soviet power and the reassurance this gave the West. Stalin, Khrushchev, and Brezhnev may have had many reasons for competing …