Via Yglesias, Justin Logan asks an interesting question:
Realists talk a lot about structure in the international political context: various structures of the balance of power push states in one direction or another. If Mexico were twice as powerful as the United States, different structural forces would be acting on us. Realists note that structures “shape and shove” but don’t determine foreign policies. Kenneth Waltz memorably wrote in 1997 that states “are free to do any fool thing they care to, but are likely to be rewarded for behavior that is responsive to structural pressures and punished for behavior that is not.”
One of the things that’s really curious about today’s world (and another about which Walt has written) is the strange condition of unipolarity. Given the size of the power disparity between the United States and, well, everybody else, there are few structural constraints acting on American policymakers. So one major input, structure, that should play a powerful role in constraining statesmen’s options, isn’t really working.
I’m not sure it’s right to think of unipolarity as a world without structural constraint. First, there are the kinds of structural constraints that realists don’t really talk about very much, such as international law, regimes, shared moral and ethical understandings, and so forth. We may think, in the wake of the Bush administration, that these mean nothing, but that’s not quite right. The Bushies thought a LOT about international organizations and international law, if only so that they could be evaded. Many of the arguments for the invasion of Iraq were presented in terms that the international community wouldn’t reject on face, and those argument affected how the United States actually behaved in Iraq. The United States did not, after all, simply declare that the Arabs needed punishment and proceed to carpet bomb Baghdad. Such an action would have disrupted the constellation of relationships that the US maintains in the international system, and that thus provide a real structural constraint on the behavior of the US. Put another way, an ideal type realist would be indifferent to signing the Kyoto Treaty; signature or no, the realist would simply ignore its provisions. The United States, even under the Bush administration, still feels bound by “squishy” structural factors, many of which we had a hand in creating.
Another response is that given by Kenneth Waltz:
To say that militarily strong states are feeble because they cannot easily bring order to minor states is like saying that a pneumatic hammer is weak because it is not suitable for drilling decayed teeth.
This is to say that unipolarity (and great power status more generally) should not be read to mean omnipotence. The United States can simultaneously enjoy unipolarity and suffer from an inability to do everything it wants, because military power simply cannot accomplish certain tasks. Thus, certain structural constraints exist, even for unipolar states. This leaves a space for domestic politics, because obviously there was disagreement in the United States in 2003 as what precisely a pneumatic hammer could do, but I suspect that structural constraints are never wholly obvious to policymakers. It also leaves a space for “squishy” structuralism, as the development of ideas such as nationalism serve as an explanation for why Britain could undertake an extended occupation of much of the known world in the 19th and 20th centuries, but the United States cannot do the same today.
One final thought, regarding Matt Yglesias “are we doomed” question; realists would almost certainly answer in the affirmative. Realists have almost invariably argued that unipolarity cannot endure, using history as their laboratory. There is much disagreement about what we mean by “endure”- twenty years, fifty years, 100 years, whatever- but the consensus is that unipolarity is not a stable distribution of power. Whether contemporaries interpret US decline as the result of a strategy of primacy, engagement, or isolation is largely irrelevant to the decline, although the decisions of policymakers may be able to slow, hasten, or cushion that decline. Even allowing this last, however, it’s unclear that contemporaries will interpret such actions in the same way as future historians.