Commentary Magazine

On the Origins of War, by Donald Kagan

Ancient Wisdom, Modern War

On the Origins of War and the Preservation of Peace.
by Donald Kagan.
Doubleday. 606 pp. $30.00.

Pity the poor statesman who turns for help to the world of ideas.

Closest to him in terms of physical proximity and overall outlook is a dense thicket of “policy intellectuals” centered in Washington, D.C. While they often have strong opinions on what to do about this or that problem of the day, these people rarely can tell the government insider anything he does not already know.

If our policy-maker ventures further afield, he will find himself wandering amidst the strange and alien subcultures of contemporary academia. Here he is likely to confront insurmountable barriers of language, outlook, and intellectual style. Political scientists are too often in the grip of theories which are highly abstract or overly deterministic (or both), and which are, as a result, of little use to policymakers. The overwhelming majority of professional historians today regard the study of statecraft with disdain.

There are still oases, however, at which the statesman may stop to draw sustenance. One of them is connected to a rich tradition of thinking about politics that originates in the historiography of the Peloponnesian war of the 5th century B.C.E. Donald Kagan, the Bass Professor of History, Classics, and Western Civilization at Yale, is this century’s premier student of that monumental struggle. Busy policymakers may feel they have nothing to learn from the past—still less from the ancient past—but Kagan’s masterful new book, ranging selectively over two-and-a-half millennia of world history, proves them wrong.

In On the Origins of War, Kagan sets out to examine a series of major confrontations: the Peloponnesian and Second Punic wars of antiquity, World Wars I and II in this century, and a “near war,” the Cuban missile crisis of 1962. Though he treats each with a historian’s respect for its complexity and distinctiveness, Kagan is also in search of answers, however tentative and conditional, to some large and general questions: what, if anything, can these very different conflicts teach us about the sources of peace and the causes of war?

Each of Kagan’s five central chapters can be read on its own with pleasure and profit; each draws together a great volume of evidence from the latest and best historical scholarship; and each is a model of analytic concision and narrative clarity. In each case, after sketching the character and objectives of the rival protagonists, Kagan proceeds down the often twisting trail of events that led them into conflict, pausing at forks in the road to show where an alternative path might have been taken and to explain why it was not.

Some of these stories will be relatively unfamiliar to contemporary readers. Thus, those who associate Hannibal only with elephants in the Alps will be interested to learn how he got there and how close he came to defeating Rome and altering the entire subsequent history of the Western world. But even when it comes to more recent and better-known events, Kagan’s interpretations are incisive, fresh, and, in some cases, controversial as well. In a brief concluding chapter Kagan makes an attempt to summarize, but the larger lessons he draws are scattered across the pages of his book and, also, lodged discreetly between its lines.



To begin with, Kagan renders a harsh judgment on the impoverished conception of human nature and its relationship to war that is harbored by so many contemporary social scientists. Most modern theorists assume that humans are primarily rational beings, an assumption that often leads to lofty visions of unstoppable progress and perpetual peace. Kagan, however, embraces another and more pessimistic conception of man, namely:

the darker picture painted by Thucydides of a human nature that remained largely the same over the centuries [and] a human race that escaped chaos and barbarism by preserving with difficulty a thin layer of civilization.

In Kagan’s view, individuals and the larger social groups into which they coalesce may be motivated in part by “interests,” by the rational pursuit of “tangible and practical goals such as wealth, prosperity, security, and freedom from external interference”; but they are also driven by other emotions and desires, among the most powerful of which are fear and the sometimes insatiable demand for “greater prestige, respect, deference, . . . honor.”

It is this mix of interests and passions that causes states to seek power and it is the pursuit of power that leads them often into war. This has been “the normal condition” of human society throughout recorded history, and there is little reason to expect it to disappear.

War, thus, may be an inevitable outgrowth of human nature. But particular wars are not. Wise and prudent policies can help to make war less likely, and foolish ones make it more so. Certain errors, as Kagan shows, recur. Overweening ambition and the restless pursuit of honor often impel leaders to abandon policies of moderation in favor of grander but disastrous new undertakings. Accordingly, Kagan’s heroes are builders and balancers like Pericles and Bismarck, and his villains are their successors, Alcibiades and Kaiser Wilhelm II, whom he sees as adventurers and extremists.

As Americans today should bear in mind, victorious powers are especially prone to misjudgment. In dealing with former foes they tend to be either unduly accommodating or excessively harsh or, worst of all, both in sequence. When confronted by rising challengers they often overestimate the extent to which such states are motivated by tangible interests (as opposed to fear or the desire for respect) and hence overstate the ease with which their opponents can be appeased or deterred.

After defeating Carthage in the First Punic War, Rome imposed a peace “of the least stable kind: it embittered the losers without depriving them of the capacity for seeking revenge and without establishing a system able to restrain them.” The Romans then were slow to appreciate the extent of the threat from a resurgent enemy intent on revenge, and were forced to pay a terrible price for their mistakes. The errors made by the democracies in dealing with Germany after World War I were thus nothing new. Had they learned the lessons of the Punic wars, the architects of the Versailles treaty would have either been much tougher or far more lenient.

As a student of statesmanship, Kagan is sympathetic to the leaders he examines, in the sense that he seeks honestly to understand their actions, but he does not shrink from assigning praise and blame. In his analysis of the Cuban missile crisis, for example, he paints a disturbing picture of John F. Kennedy’s leadership in the events leading up to and during the most dangerous confrontation of the nuclear age.

Kennedy’s weak performance in a series of foreign-policy events—the Bay of Pigs invasion, the Vienna summit, and the construction of the Berlin Wall—all helped tempt Nikita Khrushchev into deploying missiles in Cuba. The Soviet leader seems to have decided that this advance would provoke only another ineffectual response: and, according to Kagan, Khrushchev was nearly right. Were it not for overwhelming domestic political pressures, Kennedy might have been simply willing to accept Soviet rockets in Cuba in the strategically dubious belief that the location of such weapons was unimportant. (Robert McNamara, Kennedy’s Secretary of Defense, is said to have enunciated the erroneous principle justifying this position with the following words: “a missile is a missile is a missile.”)



As the events examined in this book show, there are no foolproof formulas for avoiding war. But certain approaches clearly work better than others. “[G]ood will, unilateral disarmament, the avoidance of alliances, teaching and preaching the evils of war,” writes Kagan, “are of no avail.” The renunciation of power cannot help to keep the peace. To the contrary: maintaining peace “requires active effort, planning, the expenditure of resources, and sacrifice,” the very measures that also make for success in war. Nor is the mere possession of superior power by itself adequate; the demonstrated willingness to employ it is crucial, too.

Can democracies remain strong and determined over long periods of time? On this score, Kagan has some doubts. Clearly, when sufficiently provoked, democratic regimes are quite capable of defending themselves, their interests, and their honor. But modern liberal democracies also have a deep-seated ambivalence about the acquisition and use of power (which flows from what Kagan describes as “an ethical system that is commercial, individualistic, libertarian, and hedonistic”), and their governments are under continual pressure to “satisfy domestic demands at the expense of the requirements of defense.”

Modern democracies thus may find themselves in a dangerous double bind. Hampered in the maintenance and use of their power by internal constraints, they can invite challenges because of their apparent weakness. And when such challenges come, they are not always prepared, even as they find it difficult to turn away.

As the pressures today mount for disengagement and retrenchment, Americans—statesmen and citizens alike—would do well to contemplate the practical wisdom that this important book contains.

About the Author

Aaron L. Friedberg teaches politics and international affairs at Princeton. From 2003 to 2005 he served in the office of the Vice President as deputy assistant for national-security affairs. He is writing a book about the U.S.-China rivalry.

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