GEORGE W. BUSH needs a second term at the White House. This US presidency is halfway through an experiment whose importance is almost literally earth-shattering. Its success or failure could be a beacon for the future. I want to see that experiment properly concluded.

What the President and his advisers are trying to do will be a colossal failure. But failure takes time to show itself beyond contradiction. The theory that liberal values and a capitalist economic system can be spread across the world by force of arms, and that the United States of America is competent to undertake this task, is the first big idea of the 21st Century. It should be tested to destruction. The opening American presidency of the new millennium — George W. Bush, 2001-2009 — should serve as an object lesson to the world for the decades to come. There must be no room left for argument. The President and his neoconservative court should be offered all the rope they need to hang themselves. When they do, when they fail, when America's dream of becoming the new Rome dies, there should be no possible excuse, no straw at which Republican apologists can clutch.

Throughout history, failed ideologues have protested that they were never really given the chance to put their ideas into practice. Their disciples remain, still believing, still evangelising for the next attempt. Let the former President George W. Bush find no such cult to puff his memory. Give him the chance to see this thing through to the end, so that nobody will be able to claim that it was the American people who let him down; that the voters’ nerve failed before he could finish the job. Let him finish the job. Then the failure can be pinned to him and to his project, not to any infirmity of the people’s purpose.

Incoming governments, especially if they represent big new ideas, are rarely well served when their victory leaves a lingering sense that the loser lost only the election, not the argument. It was good for Thatcherism and for Britain that in the 1974 general elections Harold Wilson was given the opportunity to resume a Labour government until five years later his successor could run it right into the buffers. We needed first to test the muddle of postwar British socialism through to its complete discredit.

We well and truly did. James Callaghan’s Government really was the last gasp of all that, and a quarter-century later one need only say “winter of discontent” to recall the total and humiliating extinction of a whole philosophy of government. The awful memory still haunts, and has moulded, its new Labour successors. Even today, even after the pain of Thatcherism, there is almost nobody alive who would with a straight face argue that a mixed economy run in partnership with organised labour is the answer for Britain.

In 1974 the British people had not despaired of corporatist government. They needed one more kick in the groin from the ghost of Karl Marx before they were ready for the shock of Margaret Thatcher. She was lucky to inherit a country which, in more than the electoral sense, had turned its back on the ideas she routed.

Tony Blair, when his time came, was lucky to inherit a similar sense of national revulsion against the former governing party. If the Tories had been ejected in 1992, Neil Kinnock would have taken the reins of a nation quite unsure what it should do next. Thatcherism had not quite run its course. A few years more were needed for the electorate to realise that her party had lost its way.

It was not John Major’s fault that he presided over a gathering storm of impatience and disgust, but he did. The storm broke in the general election of 1997, and cleared the air for his new Labour successors. Mr Blair had won the argument fair and square. He has since enjoyed the two terms that he probably deserved to prove that fine words and a lot of fiddling about cannot be a permanent prescription for government. His time, too, will come, and when it does nobody will be able to claim that the Third Way was not given a fair crack of the whip. The Third Way is dead: we have let its own originator kill it.

America’s neoconservatives deserve a similar chance. I have listened to what Senator Kerry has to say, the way he says it, and the record of what he has done in politics so far, and I cannot gather from it any sense of national direction which can rival that of Mr Bush. Mr Kerry is full of intelligent doubt, and all at sea. Mr Bush knows what he stands for.

The President is magnificently and unambiguously wrong. He has become the vehicle for a dawning neo-imperialist urge which surely had to surface now that the US has become the world’s only super- power; and he has surrounded himself with a cabal of advisers ready to turbocharge the imperialist impulse — “because we can” — with a moral energy — “because we should”.

It would have been strange indeed if a great nation, unthreatened by any rival in the world, had not felt the stirrings of an adventurism such as this. Given that the Soviet Union fell more than a decade ago, the question to Uncle Sam should perhaps be: “What took America so long?” But carried into action the new impulse is doomed. The answer to “because we can” is “you cannot”. The answer to “because we should” does not therefore arise.

What the world has begun to receive recently is a lesson in the impotence of brute power and technological sophistication. The lesson is set to continue through Mr Bush’s second term, if he gets it.

Earlier this year, before most people in Britain had even noticed that Washington was to “hand over” sovereignty to Iraq on June 30, I tried to explain on this page how the plan was doomed, and how the new government in Baghdad would be a despised puppet, ruinous to maintain, just as those long-forgotten governments of South Vietnam became. But I reckoned without the zeal which can keep such experiments alive.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden