When the American sociologist Immanuel Wallerstein titled his 2003 book The Decline of American Power, he suggested America's troubles would be the critical issue for the first decades of the new century. His view - reflecting a deep suspicion of that power's use and abuse - was inevitably a pessimistic one. Having failed to complete the project of exporting neo-liberalism to every corner of the globe, he argued, America was set on a course of inevitable decline.
It was a controversial pronouncement. But Wallerstein was not alone, and he was right about one thing: the future trajectory of the United States - mired in two wars and confronted by economic, political and military challenges across the globe - has become a matter for obsessive examination. Confronted by rising anti-Americanism, with its aura of overwhelming military supremacy undermined by two asymmetric conflicts, challenged variously by the EU, by China and India on the economic stage, and locked into a politics of fear, at first glance things do not look rosy from the Rose Garden.
Even Henry Kissinger, the veteran realist, has expressed concern that antipathy towards America is leading to a decline in its legitimacy - one of the principal weapons in America's armoury of "soft power". Has the "indispensable nation", as the former secretary of state Madeleine Albright described it, become dispensable? Has America, the world's only remaining superpower, come to a crisis precisely because of its unipolar domination?
In two new books, both Fareed Zakaria and Robert Kagan make clear that the answer is not to be found in the obvious headlines. If there is a problem, it is not located in short-term phenomena like the war in Iraq, nor even in the contours of one presidential administration. Instead, America's putative decline is bound to slower-moving and more powerful trends, the grinding tectonic plates of geopolitics and global economics. Zakaria, the suave and telegenic pundit, and editor of Newsweek International, and Kagan, the heavyweight voice of American neo-conservative theory, attack the question of American power from different positions and starting points. But if they have one thing in common, it is a dismissal of Francis Fukayama's assertion in The End of History, published in 1992, that the fall of the Soviet Union marked, perhaps, "not just the end of the Cold War, or the passing of a particular period of post-war history, but the end of history as such: that is, the end point of mankind's ideological evolution and the universalisation of Western liberal democracy as the final form of human government."
As both Zakaria and Kagan point out - inconveniently for Fukayama's thesis - history is happening again. Where they disagree is in what direction that history is taking us. Oddly, although I find myself at a polar opposite to the neo-conservative Kagan's worldview and his conclusions, his is the more satisfactory of the two books. A slight volume, only 100 pages long, there is a simple, formal elegance to both Kagan's prose and arguments that is lacking in Zakaria's book. He begins by presenting the reasons why anyone might have subscribed to the end of history in the first place.
For Kagan the notion of humanity's inevitable progress was hard-wired into western liberal thinking after the triumph of the Enlightenment's ideas. An event as massive as the collapse of the Soviet Union could only reinforce that view. "The hopes for a new era in human history rested on a unique set of international circumstances: the temporary absence of great power competition." Kagan approvingly name-checks Kissinger's warning, delivered at the end of the Cold War, that such a situation could not last - competition is a part of human nature. While it is easy to dismiss neoconservatives like Kagan as all-too-eager to search out any new threat on the horizon, his description of history's return is lucid and powerfully argued.
In a largely post-ideological world the new conflicts that Kagan identifies are between the democracies and the autocracies, not least China and Russia, functioning not as ciphers of their old Cold War configurations, but rather more like 19th century great powers. Zakaria contends that growing national wealth will lead inevitably to democratisation, an argument Kagan confidently challenges, insisting that China and Russia have proved it is compatible with autocracy as well. It is a process he argues that is occurring even as the European Union is attempting its own postmodern project of attempting to transcend national politics - a process that Kagan argues has obsessed Europeans and diverted them from the threats and challenges facing the West.
The result, according to Kagan, is the creation of a series of fragile new fault lines, each with the potential for conflict. But where does this leave America, with its sense of "universal mission", its preponderance of power and influence, and its desire to further extend that influence? Kagan's conclusions on this point are rather less satisfactory. He accepts a paradox in America's stance - a divide between a policy class eager for influence and ordinary Americans "rueful" of the costs that come with being the world's self-appointed leader - but he falls in, not surprisingly, with the former.
While Kagan acknowledges there is an American problem - and a historic one at that - of omission and commission in the pursuit and unilateral use of power, he suggests that the problems of American foreign policy will soon seem minor compared to the challenges represented by emerging autocratic powers. But his solution is a vague one: it is to continue to insist that in an increasingly troubled world the US should continue to represent democratic values, while gathering about it mechanisms for representing the ideals of the democratic world and ignoring those - like the UN Security Council - that he finds ineffectual.
If there is a fundamental problem with his worldview it is in his separation of the democrats and autocrats. It is a problem that was outlined by the historian Tony Judt in a recent essay in the New York Review of Books on the failure of historic memory in the 21st century. Essentially it is this: how can you tell the autocrats from democrats when the US - first in Kagan's view among the democrats - accepts and uses torture; when it kidnaps and disappears; when it imprisons without trial and access to lawyers, and when it launches wars outside of international law?
And while Kagan believes there is little genuine prospect of a threat to US supremacy, despite a world becoming more complex and challenging, Zakaria is not so certain. Zakaria sees the threat to the US - the return of history - not in the rise of autocracies, but in what he calls "the rise of the rest" - the economic empowerment of nations that will rival American hegemony. But Zakaria's book is far less satisfactory than Kagan's; it feels amorphous, confused sometimes, and contradictory. Niall Ferguson's criticism of Zakaria's previous book, The Future of Freedom - that there is a "sketchy quality" to his political thinking - remains unfortunately valid.
While Kagan sticks to his own tight brief, forcefully expressing his ideas, Zakaria has produced a book chock full of statistics, little anecdotes, asides and arguments both pertinent and ad hominem. While rejecting Fukayama he takes as his model Thomas Friedman's paean to globalisation, The World is Flat. The result is a book that is both fascinating, flawed and Pollyanna-ish in its view of the world. He is right, in particular, in identifying the multipolar nature of the growing challenges to American power as residing as much in the economic as the political and military sphere. But in many other instances his analysis seems almost deliberately wrong-headed.
He says that the war in Iraq has not had as much impact on the region as the doomsayers once claimed, citing the soar away success of Dubai as a counter-argument. In doing so he almost willfully ignores, for a start, the low-level conflict between Turkey and rebel Kurds now underway in the country's north, the rise of Iranian power in the vacuum left by the implosion of Iraq, and the consequences of a massive movement of refugees. And this is not the only moment that you wonder whether you are living on the same planet as Zakaria.
Elsewhere he asks rhetorically (while dismissing the proposition): "had we asked our fortune teller in 2001 to assess the effect of a quadrupling in oil prices, he would have predicted a global recession." Er, indeed, Fareed. But there is a deeper failing here. Zakaria appears transfixed by economic facts and figures, as if they were the sole determinant of human progress. Like William Butler Yeats's cruel depiction of John Keats - as a schoolboy with his "face and nose pressed to the sweetshop window" - Zakaria's face is pressed to the shop window of globalisation.
Kagan can understand that in the Russian imagination, the 1990s represent a nightmare akin to Europe's 1930s, which may explain their present determination to assert their own values against America's. Zakaria, however, cannot see much beyond the world viewed from Davos and the World Economic Forum. And it is in that other world, beyond the balance sheet, where history takes place. Peter Beaumont is Foreign Affairs Editor of the Observer newspaper in London.