The potential for the rise of a multipolar world order certainly seems far more plausible now than it did several years ago. In 2003, pundits considered the term "unipolar" to be too modest; only "empire" could capture the extraordinary position of power that the United States appeared to occupy. Indeed, in the eyes of the foreign policy commentariat, the United States has fallen from global empire to hapless Gulliver in a mere four years. When Charles Krauthammer--the columnist who originally coined the term "unipolar moment"--has announced the end of unipolarity, it is hardly a leap to suggest that multipolarity is nigh.
Perceptions of rapid polarity shifts of this sort are not unusual. In the early 1960s, only a decade after analysts had developed the notion of bipolarity, scholars were already proclaiming the return of multipolarity as postwar recoveries in Europe and Japan took off. After the fall of Saigon in 1975, they again announced the advent of multipolarity. The most influential scholarly book on international relations of the past generation, Kenneth N. Waltz's Theory of International Politics, was written in part to dispel these flighty views and show that bipolarity still endured. If one looks past the headlines to the deep material structure of the world, Waltz argued, one will see that bipolarity is still the order of the day. Yet in the early 1990s, Waltz himself proclaimed that the return of multipolarity was around the corner. Such perceived polarity shifts are usually accompanied by decline scares--concern that as other powers rise, the United States will lose its competitive edge in foreign relations. The current decline scare is the fourth since 1945--the first three occurred during the 1950s (Sputnik), the 1970s (Vietnam and stagflation), and the 1980s (the Soviet threat and Japan as a potential challenger).
In all of these cases, real changes were occurring that suggested a redistribution of power. But in each case, analysts' responses to those changes seem to have been overblown. Multipolarity--an international system marked by three or more roughly equally matched major powers--did not return in the 1960s, 1970s, or early 1990s, and each decline scare ended with the United States' position of primacy arguably strengthened.
It is impossible to know for sure whether or not the scare is for real this time--shifts in the distribution of power are notoriously hard to forecast. Barring geopolitical upheavals on the scale of Soviet collapse, the inter-state scales of power tend to change slowly. The trick is to determine when subtle quantitative shifts will lead to a major qualitative transformation of the basic structure of the international system. Fortunately, there are some simple rules of power analysis that can help prevent wild fluctuations in response to current events. Unfortunately, arguments for multipolarity's rapid return usually run afoul of them.
Rule No. 1: Be Clear About Definitions of Power
It is important to ask why opinion has gyrated so wildly from bullishness to bearishness in conversations on US power. It is not--as in some of the earlier cases--that perceptions of actual US capabilities or resources have changed. The United States is still widely recognized to be the most powerful state in a material sense since the modern international system took shape in the sixteenth century. I have conducted many of these measurements myself, and I can report that there has been no change in these "objective" indicators over the past three years sufficient enough to explain a shift in elite perspectives of US power.
What have shifted are peoples' views of the real utility of these resources and capabilities. Current discussions of the limits of US power are really focused on the limited usefulness of large amounts of military and economic capabilities. Political scientists generally use the term "power" to refer to a relationship of influence. …