Ian Clark's book joins an exclusive club: pioneering works whose theories are obsolete at publication. Yet it would be a great mistake to dismiss it. Reading Hegemony in International Society is like entering the workshop of a brainy eccentric, cluttered with a wealth of contraptions. Not all of them work as advertised, but that is no big strike against their maker. All innovation involves extravagant waste. With some inspired rummaging, Clark's workshop may still aid discovery—since scientific breakthroughs often come in close proximity to toolmakers.

At bottom, Clark intends to build an English School (ES) approach to hegemony. In his words: “The core argument is best framed as a concept of hegemony resting on more than mere measures of US material power. The latter is already adequately captured by notions of primacy or predominance…. [T]his book makes the alternative case for regarding it exclusively as a legitimate social arrangement, potentially attainable when one dominant state exists. Fundamental to this conception is that hegemony might then make a positive contribution to international order, rather than define the threat to it. Essential also is that, in contrast to most contemporary usages, no such hegemony presently exists, nor can it be in decline. In short, by hegemony is meant an institutionalized practice of special rights and responsibilities, conferred by international society or a constituency within it, on a state (or states) with the resources to lead” (p. 4).

I contend, however, that Clark's value added is not his core argument. Although others, notably Bruce Cronin, have done pathbreaking work on this topic, Clark develops the English School approach to hegemony the furthest by deploying useful analytical tools and examining a diverse set of cases (i.e., the Concert of Europe, Pax Britannica, Pax Americana, 1945–71, the United Nations, East Asia, and climate change). He is essentially right: Hegemonic legitimacy has been understudied, and we need to improve our tools to understand it. To that end, he summons a mass of concepts and distinctions. Hegemons can be made up of one or of more than one great power. Their constituency can be broad or narrow. They can be said to have more or less horizontal legitimacy among other great powers, as well as vertical legitimacy among lesser powers. These tools are unpolished gems.

The vices of this book are a match for its virtues, however. For starters, Clark's definitions obscure the theoretical contribution and undercut the policy relevance. He contrasts hegemony with primacy, which “depicts nothing beyond a distribution of power in which one state enjoys predominance” (p. 34). Therefore, hegemony excludes “those many cases better conceived as instances of material primacy alone, lacking any social sanction” (p. 35). Many cases? How many great powers have lacked all social sanction? Where is the line between primacy and hegemony with a narrow constituency? Hegemony becomes such a capacious rubric that it could double as a word for institutions that Clark likes. Primacy, on the other hand, becomes an almost empty set. As far as I could tell, only Napoleons, Nazis, and post-1971 Americans qualify for it (pp. 47, 243–44).

Note the primacy of this hegemony. On this view, hegemony and legitimacy are critical and common, and only the English School understands them. This theoretical triumph is abetted by elliptical representations of rival views (see Chap. 1, esp. p. 21). Realists might be able to recognize themselves in this work, but it would take a lot of squinting. Clark does not take seriously the strong sociological streaks in Robert Gilpin and Kenneth Waltz, and brushes aside their concerns about power corrupting. Liberals and constructivists—no novices on legitimacy either—are left to their own devices to determine how Clark's views improve upon their own. G. John Ikenberry makes repeated cameos, but never gets to use any of his good lines, while Peter Katzenstein's work on the American imperium is left out entirely. This is a surprising strategy for a book stressing cooperation and sensitivity to societal responses.

Clark's conception of legitimacy is less controversial, but the sources of legitimacy are less clear. There are hints that fair procedures, desirable outcomes (p. 57), culture (p. 66), material capability (p. 102), domestic politics (p. 121), and external threats (pp. 138, 145) drive legitimacy. But what the author is trying to explain with legitimacy is somewhat opaque, though my best guess is international influence. And with respect to influence, he asserts repeatedly that legitimacy is just as important as material capability (pp. 6, 20, 27, 35, 51).

This is a daredevil claim; the implication is that great powers could double their influence by embracing legitimacy. Imagine what the world would look like if that were true. Alas, Clark does not back it up. Some of the empirical material, particularly on Britain, is interesting, but there is little testimony from hegemons about why they chose some policies over others, or from non–great powers about why they chose to go along with hegemons.

All of this would be less troublesome were Clark not blessed with ambition. Hegemony in International Society works well as a normative book, but that is not its author's main aim. He writes that he seeks an explanation “to make ES theory relevant to … the key problem of contemporary international order: finding a stable accommodation between US power and the general interests of international society” (p. 36). American primacy is entering at least its third decade; where has the English School been?

If policy relevance is a central goal, the book falls short. Clark peppers his prose with passive voice, which vaporizes causation. Decision makers looking to craft hegemonic policies will struggle to find guidance here: the sources of legitimacy are “diverse, complex, and shifting” (p. 234), there are tradeoffs between inclusiveness and effectiveness (p. 234), and different strategies are all risky (p. 237). The author does not explain why great powers move from primacy to hegemony (or the reverse), and even if the United States wanted to practice hegemony he offers no recommendations for how to overcome the domestic and international dangers to do so (p. 244). A curious omission is the war on terror (cf. pp. 181–82). Washington, Kabul, Baghdad, and their competitors have liberally dispensed cash, coercion, and persuasion, presumably in part to win legitimacy. Clark could have illuminated this contest.

With an increasingly assertive China and an overextended United States, the future is bright for studies of hegemony and legitimacy. This book asks good questions, addresses timely and timeless topics, and provides promising building blocks for later labors. While Clark's theory is out of date today, some of his tools may come in handy tomorrow. Pretheorizing is imperative but frustrating toil, and, consistent with the spirit of this book, subsequent advancements are likely to come from inclusive, collective endeavors. Something brilliant may yet come from Clark's creative clutter.