The world is changed by idealists, according to Mikhail Gorbachev. The former leader of the Soviet Union, who is 80 this week and who is interviewed in The Independent on Sunday today, offers an insight into how far our thinking is still dominated by assumptions of the Cold War. "I think even the United States doesn't need to be a superpower," he says. "China doesn't need to be a superpower. It's a different world. Relations in the world are different."
Yet the fall of President Zine el- Abidine Ben Ali in Tunisia and, more so, that of President Hosni Mubarak in Egypt exposed the old thinking behind much of western foreign policy. In a hangover from the Cold War, our government and that of the United States had long preferred to do business with strong, autocratic leaders rather than to strike moral poses about their people's lack of freedom.
The reasons that Mr Mubarak was praised by Tony Blair as "courageous" and a "force for good", even as his government crumbled, were that he had been friendly to the West, he had provided a stable environment for business and he had been pragmatic in his dealings with Israel. The unspoken calculation was that this was preferable to the kind of government that might be thrown up by free elections, given the strength of Islamism in Egypt.
The paradox is that Mr Blair, and the George Bush administration, were in other cases the over-enthusiastic proponents of the opposite doctrine: that dictators should be ousted, by military force if necessary, and democracy should be imposed on their countries from outside. That kind of idealism, which was the right approach in Kosovo and, in the early days, in Afghanistan, was discredited by the disastrous misjudgement over toppling Saddam in Iraq.
It was that misjudgement in Iraq that led – through the obsession with terrorism and weapons of mass destruction (WMD) – to the opposite misjudgement in Libya. Having discredited the case for military action, Mr Bush and Mr Blair adopted the opposite policy towards Muammar Gaddafi, of engagement: trade, oil deals, training his army and supplying him with arms. (It was through luck rather than good judgement that most of Colonel Gaddafi's British-trained army now seems to have defected.) The payback for this engagement was that Colonel Gaddafi would give up his WMD programme – yet a defector last week claimed that he still had biological and chemical weapons.
The Independent on Sunday had hoped that David Cameron had learnt the lessons of Mr Blair's errors of judgement, and would be able to follow a middle course. There was a chance, as the Arab uprising began, that Britain could play its part, alongside an American president willing to extend the hand of friendship to peoples demanding freedom, in at last getting the balance right.
Mr Cameron did well, at the start of last week, to go to Tahrir Square in Cairo and put himself on the side of the people. He was absolutely right to say in Kuwait that the claim that "Arabs or Muslims can't do democracy... borders on racism." But the rest of the week has been disastrous for the British Government, as John Rentoul writes today. It quickly emerged that the Prime Minister was travelling to the region with a delegation of arms salespeople, aiming to do business with the autocracies of the Gulf (see George Walden's article today). That gave Douglas Alexander, Labour's Foreign Affairs spokesman, the chance to say: "This week has exposed the intellectual weakness of a UK foreign policy based on commerce."
The Foreign Office's inability to organise the prompt evacuation of British citizens from a crisis zone of which it had had ample warning was a further embarrassment, but it is the failure of Mr Cameron and William Hague to rise to the scale of events that is more worrying.
What is happening in north Africa, and what may happen in the rest of the Africa, the Middle East and Iran, is a democratic revolution comparable to the fall of Soviet totalitarianism. It will have unpredictable consequences, just as Mr Gorbachev's revolution led to the independence of the Ukraine and many other parts of the former Russian empire.
But the Prime Minister ought to make it clear that Britain, and its allies in Europe and America, see their long-term interests as being served, not by selling arms to undemocratic governments, but by allying with the idealism of the peoples of the world as they demand their freedom.