When one state is preponderant in power resources, observers often refer to the situation as hegemonic. Today, many pundits argue that other countries’ rising power and the loss of US influence in a revolutionary Middle East point to the decline of “American hegemony.” However, the term is confusing. For one thing, possession of power resources does not always imply that one can get the outcomes one prefers. Even the recent death of Osama bin Laden at the hands of US special forces does not indicate anything about US power one way or the other.
To see why, consider the situation after World War II. The US accounted for more than one-third of global product and had an overwhelming preponderance in nuclear weapons. Many considered it a global hegemon. Nonetheless, the US was unable to prevent the “loss” of China, “roll back” communism in Eastern Europe, prevent stalemate in the Korean War, defeat Vietnam’s National Liberation Front or dislodge the Castro regime in Cuba.
Even in the era of alleged American hegemony, studies show that only one-fifth of the US’ efforts to compel change in other countries through military threats were successful, while economic sanctions worked in only half of all cases. Yet many believe that the US’ current preponderance in power resources is hegemonic and that it will decline, like that of Britain before it. Some Americans react emotionally to that prospect, though it would be ahistorical to believe the US will have a preponderant share of power resources forever.
However, the term “decline” conflates two different dimensions of power: absolute decline, in the sense of decay or loss of ability to use one’s resources effectively, and relative decline, in which the other states’ power resources become greater or are used more effectively. For example, in the 17th century, the Netherlands flourished domestically, but declined in relative power as other states grew in strength. Conversely, the Western Roman Empire did not succumb to another state, but instead to internal decay and swarms of barbarians. Rome was an agrarian society with low economic productivity and a high level of internecine strife.
While the US has problems, it hardly fits the description of absolute decline in ancient Rome, and the analogy to British decline, however popular, is similarly misleading. Britain had an empire on which the sun never set, ruled more than a quarter of humankind and enjoyed naval supremacy. However, there are major differences in the relative power resources of imperial Britain and the contemporary US. By World War I, Britain ranked only fourth among the great powers in terms of military personnel, fourth in GDP and third in military spending. The costs of defense averaged 2.5 percent to 3.4 percent of GDP and the empire was ruled in large part with local troops.
In 1914, Britain’s net export of capital gave it an important financial kitty to draw upon (though some historians consider that it would have been better to have invested the money in domestic industry). Of the 8.6 million British forces in WWI, nearly one-third were provided by the overseas empire.
With the rise of nationalism, however, it became increasingly difficult for London to declare war on behalf of the empire, the defense of which became a heavier burden. By contrast, the US has had a continental-scale economy immune from nationalist disintegration since 1865. For all the loose talk of a US empire, the US is less tethered and has more degrees of freedom than Britain ever had. Indeed, the US’ geopolitical position differs profoundly from that of imperial Britain: While Britain faced rising neighbors in Germany and Russia, the US benefits from two oceans and weaker neighbors.