FLORENCE ― At the recent annual meetings of the American Economic Association, there was widespread pessimism about the future of the United States. “The age of American predominance is over,” declared one economist. “The U.S. should brace for social unrest amid blame over who was responsible for squandering global primacy,” said another.

We have heard this story many times before, not only in the U.S., but in other places as well. George Dangerfield’s controversial history, “The Strange Death of Liberal England,” describes his country’s sudden decline at the peak of its power at the turn of the last century. The world everyone knew simply and inexplicably seemed to disappear. Many Americans ― think of the Tea Party’s adherents, for example ― fear that something similar is happening to their own country. Or that it has already happened.

Dangerfield based his diagnosis on a cross-section of institutions, politics, and personalities, set against the bitter class warfare of the time. Americans, however, have generally been averse to class warfare. True, the U.S. has been home to a rigid, albeit comparably fluid, class structure ever since its founding. But Americans just don’t like to talk about it, even when they are whining about the follies of the “elite.” Nearly all Americans, apart from the richest and poorest, define themselves as “middle class.” Such remains America’s democratic ethos.

Still, it is right to ask if the American way of life will survive the 21st century, and, if it does, whether it will survive in America or migrate elsewhere as the U.S. economy and political system collapse under the accumulated weight of decades of myopic national leadership and squandered opportunities. Indeed, Chinese President Hu Jintao’s recent trip to Washington was seen by many ― particularly many Chinese ― as the passing of the torch.

Pessimists have been saying this for a long time. Optimists, touting GDP and other indicators, will continue to insist that Americans have never had it so good. If there is any continuity worth underscoring, it is the regular cohabitation of boosterism with declinism: America’s glass is always simultaneously half full and half empty.

It is no coincidence that during the Reagan/Bush years ― the last time so assertive a foreign policy coincided with such large deficits ― a book like Joseph Nye’s “Bound to Lead” (1990) could follow in the footsteps of Paul Kennedy’s “The Rise and Fall of Great Powers” (1988). The former made a strong case for the necessity of American global hegemony; the latter warned of “imperial overstretch.”

Both authors based their arguments on an assessment of the underlying context ― that is, the structure ― of world power. America was overstretched because its global liabilities were increasingly out of balance with its national assets, and it was bound to lead because the world as we know it is arranged favorably for it to do so.

Similar arguments have been raised again recently. Writers Parag Khanna and Fareed Zakaria have regurgitated those made by Kennedy, Nye, and forebears like Hedley Bull in asserting that the U.S. must lead the world away from a “new medievalism” amid the “rise of the rest” and the relative stagnation of the “West.”

But are such writers making a valid point? If we look at moments of so-called structural convergence ― the 1880s, 1920s, 1950s and 1960s, and 1990s, in particular ― we see the sources of American prosperity and power emerged in a global context, only to recede again. Perhaps rise and fall is more of a cyclical than a linear phenomenon.

Or maybe it’s neither. The missing variable in most of these arguments, even Nye’s, is leadership. Leaders are never bound to rise or fall by circumstances alone. Most historians place leadership in the foreground of human history, with structural variables having conditional, not causal, value. Beneath even the richest soil, Dangerfield wrote, may lie the most perilous residue of discord and destruction.

Why have Americans been so good at leading? Are Americans specially blessed or just lucky? Now that the U.S. has at last begun to move, gradually and thoughtfully, away from the passions that characterized the country’s response to the 2001 terrorist attacks, it is worth asking if Bill Clinton was right to say that America’s virtues and assets always prevail against its vices and defects.

The writers mentioned above are less interested in the essence of power than in its exercise. They would rather have the U.S. become more sophisticated in the ways of the world. Khanna, for example ― presumably drawing upon the recent writing of Edward Luttwak ― urges Americans to learn from the Byzantine Empire in crafting complex and obscure alliances among large and small states and non-state entities, so that diplomacy comes to resemble something like the global derivatives market.

Americans don’t do this particularly well, however Byzantine their country’s own politics and policy-making may seem. Which takes us back to structure. The U.S. political system was never designed to rule the world. Its checks and balances were meant to frustrate any such mission at the hands of an all-powerful executive, and it is doubtful that Americans would support such activism in perpetuity.

The secrets of American success are transparent yet difficult to quantify. Americans’ pragmatism, opportunism, fair-mindedness, inventiveness, adaptability, optimism and, above all, their inherent competitiveness offset their tendencies toward violence, impatience, self-righteousness, and unpredictability, their fondness for novelty and celebrity for their own sake, and their self-assertion en masse ― getting there, as they like to say, “fastest with the mostest.”

Those who understand Americans’ deep-rooted passion for “making it” know why class or any other civil warfare has not succeeded in destroying America from within. The American character prefers displacement to destruction, the win-win to the zero-sum. That is still true, both at home and abroad.

By Kenneth Weisbrode

Kenneth Weisbrode is a diplomatic historian. His most recent book is “The Atlantic Century.” ― Ed.

(Project Syndicate)