The best defense.

• Author: Posen, Barry R.
• Position: Books

John J. Mearsheimer, The Tragedy of Great Power Politics (New York: W.W. Norton, 2001), 448 pp., $27.95.

THE ABSENCE of a sovereign in international politics, the root of what structural realists call the condition of anarchy, encourages states to look to their own security. Power, especially the power to wage war, is the means to this end, and states try to accumulate power because in the event of aggression by others, they must rely on themselves; they live in a "self-help" world. All "structural" realists agree on this point. Where they have come to disagree in recent years is whether states "satisfice", in Herbert Simon's artful term, or "maximize." (1) Do they struggle for power until--for whatever reasons--they feel reasonably secure? Or do they struggle on until they achieve something like hegemony--the domination of their political environment (however they define both domination and environment)?

The "satisficers" are now called defensive realists; the "maximizers" offensive realists. John J. Mearsheimer, in The Tragedy of Great Power Politics, establishes himself as the leader of the offensive realists, for his is the first systematic, historically grounded statement of the "theory of offensive realism." Informally, Mearsheimer's analysis also constitutes a test of that theory. The result is a superb book: the theory is stated with admirable clarity; evidence is marshaled by the battalion. Though the non-specialist reader must assimilate a slightly esoteric set of terms, there are only a few of them and they are so colorful that Mearsheimer need only explain them once. Few international relations theorists would introduce a new term into political science such as "bait and bleed strategy"; perhaps more should do so because the reader does not easily forget such evocative language. Anyone interested in international politics can read, enjoy, understand and argue with this book. It is not without probl ems, which will be taken up below--but first to the argument.

The Theory

REALISTS, OR rather "structural realists" as they have been termed since the publication of Kenneth Waltz's Theory of International Politics in 1979, believe that broad patterns of behavior among the most powerful states in international politics over hundreds of years can be explained by the fact that all states must deal with the same problem: anarchy. This critical problem shapes the way states live. States must look to their own defense. They arm when they might prefer not to. They ally with countries they loathe. They might even start wars when they prefer peace. States work hard to make themselves secure. Nevertheless, many structural realists--sometimes dubbed "defensive realists"--believe that despite the condition of anarchy, states will stop well short of hegemony if geography or technology or social organization favors the defense. States seek power as a means to an end--security. Starting from a world of fear and struggle, defensive realists come to a qualifiedly optimistic conclusion: that, at le ast in theory, conditions exist under which all states can be safe, even in anarchy. Wars could still happen for any number of reasons, but violent struggle for security may not be inevitable.

Mearsheimer also believes that states seek power to attain security, but he argues that so long as anarchy exists, no state can ever be truly secure. He asserts that even powerful states will seldom believe they have enough power to remain secure so long as others have significant power. Instead, states will keep trying to add to their power. They will try to maximize relative power by moving to increase their share of all the power in the world. Indeed, any state that gets the chance will bid for hegemony: it will try to make itself unchallengeable militarily by any state capable enough, and close enough, to ever threaten it with damage. This is a key disagreement between offensive and defensive realists. There is no happy ending for Mearsheimer, hence the "tragedy" of great power politics in his title.

Mearsheimer does not argue, however, that all states seek hegemony all the time. Most lack the capacity to achieve hegemony, and though they are interested in improving their relative power position, they are also interested in protecting their existing power position, which their attempts at aggrandizement may jeopardize. But what kind of hegemony do capable states seek? Mearsheimer argues that they bid for regional hegemony.

A regional hegemon seeks to be the most powerful state in its surrounding area, especially on land. If strong enough, it will wage war to finish off any "near peer" competitors around it. The power of a state derives from the size of its economy and its population, but these factors must be distilled into "land power" for a state to be a great power. Mearsheimer argues that land power is the most important kind in international politics because land power wins wars. Land power is based mainly on the size and quality of a state's army and, in modern times, the air and naval capabilities that contribute directly to the striking power of armies. Aspiring hegemons, therefore, seek to be the most capable land power in their region, and by a very substantial margin.

Aspiring hegemons cause most of the excitement in international politics: ultimately, other states that value their sovereignty have to stop them, but their efforts to contain aspiring...