The aim of al-Qaeda never was the collapse of the West. It was the withdrawal of American troops from Saudi Arabia, together with larger aspirations for the revival of the Caliphate and the reemergence of the Umma as a world power. But the collapse of the West was foreseen. It was not an aim but a consequence, and it followed from Ibn Khaldun's theory of the decline and fall of civilisations.

Has it happened? Not yet. But ten years on, the United States has been humiliated into renegotiating its trillions of dollars of debt. Western economies, almost all of them, are ailing. The European Union is under strain, its future in doubt. There have been riots and looting on the streets of London and Manchester, just as there have been in recent years in France, Greece and Spain. The global economy looks far less stable than it did before the collapse of 2008. In Europe, following a series of scandals, bankers, politicians, journalists and even the police have been tried and found wanting. Those who read the runes of the future are turning their eyes eastward to India, China, and the fast-growing economies of south-east Asia. The West no longer looks invincible. As a narrative, the "end of history" has proved less predictive than the "decline of civilisations". So far, Hegel 0, Ibn Khaldun 1.

The real challenge of 9/11 is not what it seemed at the time: Osama bin Laden, al-Qaeda, Sayyid Qutb and radical Islam. These were real and present threats, to be sure, but they were symptoms, not cause. The challenge was the underlying moral health of Western liberal democracies, their asabiyah, their sense of identity and collective responsibility, their commitment to one another and to the ideals that brought them into being. The counter-narrative of 1989 and the fall of Soviet Communism saw it not as a victory for the West but as part of a law of history that says: all great civilisations eventually decline, and the West will be the next to go.

That view is not limited to enemies of the West. It was most recently stated by the Harvard historian Niall Ferguson in his Civilization: The West and the Rest. It was most powerfully formulated by Alasdair MacIntyre in his masterwork, After Virtue. My favourite version of it comes from Bertrand Russell in the introduction to his History of Western Philosophy, speaking about the tendency of the most creative civilisations to self-destruct:

What had happened in the great age of Greece happened again in Renaissance Italy. Traditional moral restraints disappeared, because they were seen to be associated with superstition; the liberation from fetters made individuals energetic and creative, producing a rare florescence of genius; but the anarchy and treachery which inevitably resulted from the decay of morals made Italians collectively impotent, and they fell, like the Greeks, under the domination of nations less civilised than themselves but not so destitute of social cohesion.