Kenneth Waltz and the Power of Pure Theory

Waltz had a gift for rigorously linking the theoretical with the practical.

Kenneth Waltz died this week, just shy of his 89th birthday. I can’t say that I knew the famous Berkeley scholar well, though I did once have lunch with him early in my career. It was a harrowing experience for me as he challenged me about why I thought the Third World mattered. I learned later that my noontime grilling was nothing compared to the tough love he gave his students, who invariably remember him with deep respect and affection but also still present some of the symptoms of post-traumatic stress disorder.

But what all of us in the field of international relations experienced on a regular basis was the power of Waltz’s intellect, which towered over the discipline and inspired all of us who inclined toward a realist approach with his application of rigorous theory to the most important practical issues statesmen grappled with.

Waltz’s scholarly stature was due entirely to the force of his intellect and his willingness to challenge prevailing orthodoxies. He never served in government. And while his writings touched on many of the major events of the day—Vietnam, nuclear proliferation, the Cold War—he did not aspire to be a public intellectual.

Instead, Waltz made his mark through a handful of books and articles in which he advanced simple, yet counterintuitive, theories about how international politics works. His theories often struck other scholars as implausible at first, but their logic often proved irresistible over time. And when he applied his theoretical insights to the real world, they regularly made sense of some otherwise puzzling things.

Waltz wrote three major books, but his magnum opus was his 1979 Theory of International Politics, which is widely regarded as the urtext of modern Neorealism. In it, Waltz employed a unique combination of political theory (his surprising debt to Immanuel Kant would make a great doctoral dissertation) and modern economic reasoning to produce a system-level theory of international relations.

In contrast to the dominant “reductionist” theories of international relations that focused on traits within individual states to explain their behavior, Waltz offered a theory of international relations based upon factors at the level of the system itself. For example, he argued that the number of major powers (the distribution of capabilities), rather than their culture or the nature of their political systems, determined the stability of the system.

Waltz was, of course, not the first theorist of international relations to explore how the system’s “polarity” affected its dynamics, but his was the most logically rigorous of all such theories. He also maintained, in contradiction to many other systems theorists, that the most unstable systems were those with three or more powers (multipolarity) or those with only one power (unipolarity).

Indeed, he is famous for his argument about the stability of a bipolar world. In a 1964 article, written at the height of the Cold War, Waltz argued that the U.S.-Soviet rivalry was likely to be stable on two grounds: Such a configuration of power would reduce uncertainty because the two great powers had to focus only on each other. And bipolarity also lessened conflict because each of the poles would rely mainly on its own internal resources to balance the other, eliminating the need to compete with each other over third parties. From our post-1989 perspective, the “long peace” of the Cold War may have seemed inevitable, but Waltz advanced this radical argument just two years after the Cuban Missile Crisis.

Like many college professors, Waltz became skeptical of growing U.S. involvement in the war in Vietnam. Of course, he was not the only, or even the most prominent, realist critic of the war. That distinction would go to the University of Chicago’s Hans Morgenthau. But whereas Morgenthau’s critique of the Johnson administration’s policies in Vietnam was that they were ill-advised from the standpoint of U.S. national interests, Waltz offered a more systematic assessment of precisely why that was the case.

Waltz’s structural perspective led him to conclude that Vietnam, and indeed most other parts of the Third World, were not a decisive element in the larger U.S.-Soviet rivalry because bipolarity encouraged internal, rather than external balancing. This conclusion followed ineluctably from his structural theory of international politics. It was also prescient: Despite the United States “loss” of South Vietnam in 1975, the balance between the two was hardly upset by the loss of this part of the Third World.

One could fairly complain that Waltz’s arguments about the stability of a bipolar world lulled realists into a false sense of complacency about the perpetuation of the Cold War. This may have resulted from what a younger realist critic calls Neorealism’s “status quo bias.” Yet even here Waltz anticipated that the Cold War was likely to end via Soviet exhaustion. As he wrote in Theory of International Politics, “With half our GNP, [the Soviet Union] has to run hard to stay in the race. One may think the question to ask is not whether a third or fourth country will enter the circle of great powers . . . but rather whether the Soviet Union can keep up.”

Despite its alleged failure to anticipate the end of the Cold War, Waltz’s structural theory was also relevant to the post-Cold War debate about U.S. primacy. Whereas Waltz saw bipolarity as stable and enduring, the logic of his structural theory led him to predict that the U.S.’s “unipolar moment” was likely to be fleeting because other states would eventually balance against us.