What’s your favourite fact? Come on, everyone has a favourite fact. Here’s mine: more young people supported the Vietnam War than did any other section of the American population. As the war progressed, the whole country turned against it, but those under 30 remained least likely to regard it as an error.

I have deployed this point on countless occasions — arguments about the Sixties, disputes about the political views of young people, discussions on the differences between the views of activists and the general public — but I bring it up now for a different reason. The man from whom I first learnt it (it was in one of his many books) died last week.

The sociologist and political scientist Seymour Martin Lipset was 84 and had been ill for some time. His name is unknown to almost everybody in this country. Not so the political grouping of which he was a founder member. The small group of Trotskyites with whom Lipset associated when he was a student at City College in New York grew up to become known as the neocons. Lipset’s contribution to their thinking was critical.

Neocon has become the ultimate term of political abuse, a description of an alien idea foisted on an unwary nation by hardline conservatives. Can I take a few moments on the occasion of Lipset’s death to suggest that this isn’t quite right? Let me start with the most common misconception of all, with an error that Lipset’s career exposes quite clearly. Neoconservatism is thought to be a doctrine of the Right. It isn’t. It is a critique of the Left. And the difference is important.

A few years ago Lipset met General Colin Powell at a cocktail party. The academic joked to the soldier that they had both been born in Harlem, brought up in the Bronx and graduated from City College. Later he wrote: “I failed to add what was more relevant, that he joined the Reserve Officers Training Corps, while I joined the youth section of the Young People’s Socialist League, Fourth International.”

Why more relevant? Because it was while trying to make sense of the failure of American socialism that Lipset began to develop one of the central tenets of neocon thought — American exceptionalism.

Lipset’s work began with a simple observation — that socialist parties enjoyed considerable success throughout Europe but had failed entirely in America, even in the years of the Great Depression. The mystery was one that exercised socialists a great deal. In the early years of the 20th century they had believed that the US would be the first place to usher in a socialist republic. Within a few decades Stalin was attending a special commission of the Communist International to discuss the perplexing “American Question”.

The young American scholar turned to the work of Alexis de Tocqueville for an answer, to his idea of “American exceptionalism”. America, went the argument, is different. Lacking a feudal past, it is more socially egalitarian, more meritocratic, more individualistic and more rights-orientated. It also rejected state religion; instead individuals enjoy a personal relationship with their God.

The spirit of the Revolution made America the land of liberty, anti-statism and individualism. Lipset was always ambivalent about this. He regretted the country’s high crime rates, insecurity and extremes of wealth. Later in life he would write a book entitled American Exceptionalism: A Double-Edged Sword. But on one thing he was clear: on American soil, socialism, even social democracy, could not take root.

From this insight, Lipset’s insight, flowed most of neoconservative thinking. On the domestic front neocons discussed the sort of welfare provision that could survive in such an inhospitable climate. They began to argue that protecting bourgeois values was essential in a country with a small State. And this led to a clash with another part of the Left — the New Left, intent on challenging the traditional American way of life.

There was also foreign policy. If America was different — if it was, uniquely, a state created to advance liberty — didn’t it have a mission? Shouldn’t it resist the oppression of totalitarian ideologues? Shouldn’t it promote freedom around the globe? This led to a second breach with others on the Left. The neocons lost patience with what they saw as the soft attitude the rest of the Left had toward communism. When the Cold War ended, neocons continued to talk of a global mission to combat totalitarianism. Not all, however, supported the Iraq war.

I said that understanding neoconservatism as a critique of the Left (even this title was foisted on the group by a socialist opponent, Michael Harrington, as an attack on their Left credentials) was important. Why? Because the neocons are not trying to guide America to a new policy. Instead they are trying to interpret the traditions and spirit of the country. As Robert Kagan argues in his new book Dangerous Nation: “This enduring tradition has led Americans into some disasters where they have done more harm than good, and into triumphs where they have done more good than harm. These days this conviction is strangely called ‘neoconservatism’, but there is nothing ‘neo’ and certainly nothing conservative about it. US foreign policy has almost always been a liberal foreign policy.” And if this is right, it means that the policy advocated by neocons will long survive their own departure from the scene.

One more episode in the intellectual journey of Seymour Martin Lipset is worth recording. Very near the end of his life, before a debilitating stroke rendered him unable to speak, the great political scientist turned his attention to a new development — the third way social democracy of Tony Blair and Gerhard Schröder.

America, he argued, was still different, but it had become less exceptional. Europe — now more meritocratic, more rights-orientated, more libertarian — was becoming like America, and it too no longer provided good soil for the traditional Left.

It’s a change I welcome but, reading Lipset, I wonder. Perhaps modern anti-Americans do not really dislike how different they are. They fear how similar we are becoming.

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