At the January meeting of the American Historical Association Professor Schroeder gave an electrifying address on the differences between imperialism and hegemony. AHA President Lynn Hunt ran up to him afterwards to implore him to write an op-ed. At our request, he did so.

American Empire is the current rage--whether hailed or denounced, accepted as inevitable or greeted as an historic opportunity. Common to the discourse is an assumption, shared also by friends and foes abroad, that America already enjoys a world-imperial position and is launched on an imperial course.

But that assumption involves another: that America is already an empire simply by being the world's only superpower, by virtue of its military supremacy, economic power, global influence, technological and scientific prowess, and world-wide alliances. The term "empire," in short, describes America's current condition and world status, and is equivalent to phrases like "unipolar moment" or "unchallenged hegemony."

This is a misleading, unhistorical understanding of empire, ignoring crucial distinctions between empire and other relationships in international affairs and obscuring vital truths about the fate of empires and bids for empire within the modern international system. A better understanding of empire can point us to historical generalizations we ignore at our peril.

First a definition: empire means political control exercised by one organized political unit over another unit separate from and alien to it. Many factors enter into empire--economics, technology, ideology, religion, above all military strategy and weaponry--but the essential core is political: the possession of final authority by one entity over the vital political decisions of another. This need not mean direct rule exercised by formal occupation and administration; most empires involve informal, indirect rule. But real empire requires that effective final authority, and states can enjoy various forms of superiority or even domination over others without being empires.

This points to a critical distinction between two terms frequently employed as synonyms: hegemony and empire. These are two essentially different relationships. Hegemony means clear, acknowledged leadership and dominant influence by one unit within a community of units not under a single authority. A hegemon is first among equals; an imperial power rules over subordinates. A hegemonic power is the one without whom no final decision can be reached within a given system; its responsibility is essentially managerial, to see that a decision is reached. An imperial power rules the system, imposes its decision when it wishes.

Powerful implications flow from this definition and distinction. First, hegemony in principle is compatible with the international system we now have, composed of autonomous, coordinate units enjoying juridical equality (status, sovereignty, rights, and international obligations) regardless of differences in power. Empire is not.

Second, those who speak of an American empire bringing freedom and democracy to the world are talking of dry rain and snowy blackness. In principle and by definition, empire is the negation of political freedom, liberation, and self-determination.

This empire/hegemony dialectic yields some profound historical lessons, offered here without proof, though historical evidence is abundant:

1) There are circumstances (the absence or breakdown of inter-state or inter-community order) under which empires have historically provided a certain order and stability, though almost always accompanied by overt and latent violence, disorder, and war. Where, however, a relatively stable international system of autonomous units already exists, attempts to make that system work and endure through empire have not only regularly failed, but overwhelmingly produced massive instability, disorder, and war.

2) Recurrently throughout modern history leading powers have at critical junctures chosen empire over hegemony, and thereby triggered large-scale disorder and war. In some instances, the choice was conscious and demonstrable, in many others less clear-cut and more debatable. Nonetheless, the historian can point to repeated instances over the last five centuries where leader and powers, having the option between empire and hegemony, chose the path of empire, and thereby ruined themselves and the system.

3) The converse also holds. Where real advances in international order, stability, and peace have been achieved (and they have been), they have been connected with choices leading powers have made for durable, tolerable hegemony rather than empire.

4) Recent developments reshaping the international system (e.g., globalization, the rise of new states, the growth of non-governmental actors and international institutions, developments in weaponry, etc.) reinforce this longstanding trend, making empire increasingly unworkable and counterproductive as a principle of order, and hegemony more possible, more needed, and more potentially stable and beneficial.

These are not academic propositions. They illuminate the choice for America today. It is not an empire--not yet. But it is at this moment a wannabe empire, poised on the brink. The Bush Doctrine proclaims unquestionably imperialist ambitions and goals, and its armed forces are poised for war for empire--formal empire in Iraq through conquest, occupation, and indefinite political control, and informal empire over the whole Middle East through exclusive paramountcy. The administration pursues this path even in the face of a far graver challenge by North Korea to both its imperial pretensions and its own and the world's security.

History here warrants a prediction, based not on analogies or examples from the past but on sober analysis of what can and cannot succeed in this international world. If America goes down the path of empire, it will ultimately fail. How, when, and with what consequences, no one can tell--but fail it will, and harm itself and the world in the process. Not the least harm will come from thereby wrecking an American hegemony now clearly possible, needed, and potentially durable and beneficial.

In July 1878, at the end of the Berlin Congress that patched up peace in the Balkans after a Russo-Turkish war, Prince Bismarck told an Ottoman delegate, "This is your last chance--and if I know you, you will not take it." Bismarck's words, slightly altered, apply today. This is our best chance--and knowing us, we will not take it. But there is hope. Circumstances, the frictions of war, the pressures and pleas of allies, the maneuvers and resistances of opponents, new foreign dangers, challenges, and distractions, and domestic problems and politics could yet deter this country from a potentially tragic choice of empire and compel it to settle for hegemony. In other words, that special Providence Bismarck once said was reserved for fools, drunkards, and the United States of America may again come to our rescue.