Hegemonic Stability Theory actually refers to several different bodies of theory, each concerned with the role of a hegemonic or superior power in global politics. The basic claim, in each case, is that the international political and economic system is at its most stable when it is under the control of a single state, the “hegemon.” A hegemonic power is one which is powerful enough to effectively control all important international rules, agreements, and institutions, through a mixture of diplomacy, persuasion, and military and economic coercion. By the same token, a country powerful enough to impose its will upon the rest of the world will establish a system of rules and norms that contribute to global stability. Charles Kindleberger (The World in Depression) has argued that the economic difficulties of the 1920s and 1930s were the result of the collapse of world leadership: Britain had not recovered from the First World War, and the United States would not assert itself until after the Second.
Several fundamental variables determine the potential of nation-states to rise to hegemonic status. Historically, they are generally islands or peninsulas, which lend them a degree of security from ground invasion. The British Empire rested upon the security of the British Isles, for instance, and the United States, though not an island, is surrounded by oceans on two sides and by relatively weak allies (Canada and Mexico) to the north and south.
Secondly, potential hegemons must have unparalleled political and economic strength. A large economy, with particular preponderance in important technological sectors, is characteristic of effective hegemons. The extent to which China possesses this characteristic, and might therefore replace a declining United States as the leading world power, is currently the subject of much debate among international relations analysts. However, according to hegemonic theory, this must be backed by the military power necessary to enforce international laws.
Thirdly, a country must actually wish to play a hegemonic role. During the interwar period, for example, the United States might have attempted to assert the hegemonic status it later did during the 1940s; however, it chose instead to pursue an isolationist foreign policy (with the exception of continued imperialism in Latin America), driven by strong domestic political pressures to avoid further foreign entanglements like the devastating Great War.
Fourth and finally, hegemonic stability theories expect that hegemonic powers, to protect their status, will commit to defending an image of an international system, rather than simply serving their own self-interest. The extent to which this ideological element is an irrelevant byproduct of power, an instance of necessary benevolence, or a cynical calculation by elites to co-opt the lower classes and poorer states depends upon which variant of the theory is being applied.
Political scientists and historians within this field identify four major hegemonic powers in the modern age: Portugal (until it was invaded by Spain), the Dutch until the Glorious Revolution in England in 1688, the British Empire from then until 1914, with a brief pause for the Napoleonic Wars), and the United States from 1945 to the present. Each of these possessed an important economic monopoly or near-monopoly central to its rise to power: the Portuguese controlled early oceanic navigation, the Dutch controlled the European money supply, the British dominated textiles, ocean transport, and early industrialization in general), and the United States controlled fossil fuels.
Hegemonic Theory and Realism
Hegemonic stability theory owes its name to neorealist political scientist Robert Gilpin (The Political Economy of International Relations and War and Change in International Politics). Fellow realist Stephen Krasner (Addressing State ) has also emerged as an outspoken advocate of American action to address failed and weak states in order to preserve international stability.
In realist terms, hegemony does not eliminate anarchy, but it does sharply limit its effects. A single power — in other words, a unipolar world order — is expected to reduce the number of conflicts among rival nations, since inequalities in power are large and therefore conflicts between two or more roughly equivalent forces are extremely unlikely.
Of course, such theories are usually espoused by those who live near the top of unipolar hierarchies of nations. Even in the absence of large-scale war, hegemonic “stability” often involves the frequent and disproportionate application of military force against weak states.
Hegemonic Theory and Liberalism
Hegemonic stability theorists departing from liberal beginnings have tended to stress the public goods created by hegemons — “goods,” or benefits, which are shared by virtually all states within the system but seldom produced jointly because self-serving countries prefer to free-ride on others’ investments. Such collective action problems are common in society, and arise whenever large numbers of people choose to benefit from others’ actions without making an appropriate investment of their own in the same project, the upshot of which is that very little is accomplished by anyone. The failure of real international cooperation to prevent global environmental degradation is a classic instance of this phenomenon.
Hegemons, according to liberals, can overcome this problem: they are sufficiently larger than other members of the state system that they can agree to take on the costs of a project almost unilaterally, and are willing to do so for the sake of the stability of the system which has put them in the privileged position they currently enjoy. This role of the hegemon as benevolent ruler has preoccupied many advocates of continued American hegemony, such as G. John Ikenberry (After Victory).