Great Powers in the 21st Century The Rise and Fall of Stephen G. Brooks and the Great Powers in William C. Wohlforth the Twenty-ªrst Century China’s Rise and the Fate of America’s Global Position Unipolarity is argu- ably the most popular concept analysts use to assess the U.S. position in the in- ternational system that emerged in the wake of the demise of the Soviet Union in 1991.1 The concept’s origins lie in a major academic literature devoted to ex- plaining large-scale patterns of behavior in international systems. The basic in- sight is that the number of powerful states or “poles” at the top signiªcantly inºuences how international politics works. In recent years, however, the concept has been more likely to serve a rather different purpose: to gauge change in today’s international system. In response to the ªnancial crisis of 2008 and the continued economic ascent of China, pundits, policymakers, gov- ernment analysts, and scholars frequently and prominently argue that the United States has tumbled from its dominant position and that a fundamental, system-altering power shift away from unipolarity is occurring. “Unipolarity is ending, has ended, or will soon end,” goes the gist of much commentary, “and the system is reverting to multipolarity or bipolarity or apolarity” or whatever neologism the analyst wishes to propound.2 Stephen G. Brooks is Associate Professor of Government at Dartmouth College. William C. Wohlforth is Daniel Webster Professor of Government also at Dartmouth. This article draws upon their forthcoming book America Abroad: The United States’ Global Role in the 21st Century (Oxford: Oxford University Press). The authors acknowledge with thanks written comments from Jeff Friedman, Andrea Gilli, Mauro Gilli, Gardiner Kreglow, Alexander Lanoszka, Jonathan Markowitz, Joseph Singh, and the anony- mous reviewers, as well as feedback from participants in seminars at Aberystwyth University, the Brookings Institution, Brown University, the Cato Institute, Columbia University, Dartmouth Col- lege, George Washington University, Georgetown University, Johns Hopkins Applied Physics Lab- oratory, the London School of Economics, Moscow State Institute of International Relations, the Massachusetts Institute of Technology’s Lincoln Laboratory, Northeastern University, Ohio State University, the Tobin Project, the University of Cambridge, the University of Ottawa, the Univer- sity of Oxford, and the U.S. Naval War College. They are also grateful to Michael Beckley, Tai Ming Cheung, Thomas Culora, Allan Dafoe, Andrew Erickson, Taylor Fravel, Eugene Gholz, Charles Glaser, Lyle Goldstein, Jim Holmes, Adam Liff, Jon Lindsay, Austin Long, Stephen Macekura, Mi- chael Mastanduno, James Mattis, Evan Montgomery, William Murray, Keshav Poddar, Barry Posen, Daryl Press, Jeremy Shapiro, Andrew Winner, Thomas Wright, and Riqiang Wu for their help at various stages of this project, and to Joanne Hyun, Holly Jeong, Ming Koh, Gardiner Kreglow, Yerin Yang, and Yannick Yu for their excellent research assistance. 1. Notable initial contributions include Charles Krauthammer, “The Unipolar Moment,” Foreign Affairs, Vol. 70, No. 1 (Winter 1990/91), pp. 23–33; Ethan B. Kapstein and Michael Mastanduno, eds., Unipolar Politics (New York: Columbia University Press, 1999); and William C. Wohlforth, “The Stability of a Unipolar World,” International Security, Vol. 24, No. 1 (Summer 1999), pp. 5–41. 2. The approach of a post-U.S., multipolar world is envisioned in best-sellers by the likes of International Security, Vol. 40, No. 3 (Winter 2015/16), pp. 7–53, doi:10.1162/ISEC_a_00225 © 2016 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology. 7 Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/ISEC_a_00225 by guest on 01 October 2021 International Security 40:3 8 In this article, we show that this approach to assessing changing power rela- tions in today’s international system is irreparably ºawed, and we develop an alternative. The very qualities that make the concept of polarity helpful for capturing some key differences in how international systems work render it unhelpful for assessing changes within a given system. Use of the concept helps analysts understand why a world with one superpower is different in important ways from one with two superpowers or none, but it is too blunt an instrument to track change from one kind of system to another. On glaring dis- play as the Cold War neared its end in the late 1980s, this pitfall of polarity is an even bigger problem today. Because China is unlike past rising powers and because the world in which it is ascending is also different in important ways from previous eras, careful thinking about how today’s one-superpower world might change into something else is at a premium. Using a set of concepts and measures geared precisely to this challenge, we show that the United States will long remain the only state with the capability to be a superpower. Still, China’s rise is real and change is afoot, and the arguments we develop herein will help analysts assess and classify this change without either downplaying or exaggerating its systemic signiªcance. We begin by demonstrating the ways in which the concept of unipolarity leads analysts astray when assessing changes in the distribution of capabilities in the international system. Three analytical pitfalls stand out: (1) use of the concept of polarity encourages dichotomous thinking—the world is either unipolar or multipolar (or bipolar)—and thereby feeds an artiªcial debate about whether everything is changing or nothing is changing;3 (2) it demands Fareed Zakaria and Parag Khanna, as well as in forecasts by the National Intelligence Council and numerous prominent private sector analysts from Goldman Sachs to the Eurasia Group. See Zakaria, The Post-American World (New York: W.W. Norton, 2009); Khanna, The Second World: How Emerging Powers Are Redeªning Global Competition in the Twenty-First Century (New York: Random House, 2009); National Intelligence Council, Global Trends 2025: A Transformed World (Washington, D.C.: Government Printing Ofªce, 2008); and Ian Bremmer, Every Nation for Itself: Winners and Losers in a G-Zero World (New York: Penguin, 2012). Prominent scholarly treatments include Chris- topher Layne, “This Time It’s Real: The End of Unipolarity and the Pax Americana,” International Studies Quarterly, Vol. 56, No. 1 (March 2012), pp. 203–213; Amitav Acharya, The End of American World Order (New York: Polity, 2014); and Barry R. Posen, “From Unipolarity to Multipolarity: Transition in Sight?” in G. John Ikenberry, Michael Mastanduno, and William C. Wohlforth, eds., International Relations Theory and the Consequences of Unipolarity (New York: Cambridge University Press, 2012), pp. 317–341. 3. For studies that come closest to adopting the contrarian “nothing is changing” position, see Mi- chael Beckley, “China’s Century? Why America’s Edge Will Endure,” International Security, Vol. 36, No. 3 (Winter 2011/12), pp. 41–78; Michael Beckley, “The Unipolar Era: Why American Power Per- sists and China’s Rise Is Limited,” Ph.D. dissertation, Columbia University, 2012; Stephen G. Brooks and William C. Wohlforth, World Out of Balance: International Relations and the Challenge of American Primacy (Princeton, N.J.: Princeton University Press, 2008); Stephen G. Brooks and Wil- liam C. Wohlforth, “Assessing the Balance,” Cambridge Review of International Affairs, Vol. 20, No. 2 (June 2011), pp. 201–219; Robert J. Lieber, Power and Willpower in the American Future: Why the United States Is Not Destined to Decline (Cambridge: Cambridge University Press, 2012); Robert Downloaded from http://www.mitpressjournals.org/doi/pdf/10.1162/ISEC_a_00225 by guest on 01 October 2021 Great Powers in the 21st Century 9 broad, transhistorical measures of the distribution of capabilities that in- evitably fail to capture crucial shifts in the wellsprings of state power across time; and (3) the concept is ill equipped to capture the relationship between structure and agency—namely, how likely it is that state action can alter the system. The second section presents a systematic examination of the distribution of capabilities tailored to twenty-ªrst-century global politics and the requisites of superpower status. We ªnd that the United States will long remain the world’s sole superpower, but that China’s economic ascent is a major change that deserves the intense focus it has attracted. It has put China in a class by it- self, one that the polarity concept cannot capture: greater than other major powers such as Germany, Japan, and Russia but nowhere near a peer of the United States. Third, we assess the speed with which China might transform the current one-superpower system into a different kind of system. We delineate three key differences from previous eras that invalidate analogies to the power transi- tions chronicled in Paul Kennedy’s classic The Rise and Fall of the Great Powers.4 First, unlike past rising powers, China is at a much lower technological level than the leading state. Second, the distance China must travel is extraordi- narily large because the size of the U.S. military advantage is much bigger than the analogous gaps in previous eras. Third, the very nature of power has changed: the greatly enhanced difªculty of converting economic capacity into military capacity makes the transition from a great power to a superpower much harder now than it was in the past. This analysis yields a new frame-