Such is Britain's cultural deference to American values that any incendiary political volume that tops the New York Times bestseller list will, despite its irrelevance to our political culture, appear here with hoopla. Hence the LA Times columnist Jonah Goldberg's invective against American liberalism being published by Penguin.

Oscar Wilde's notion that Britain and the US are divided by a common language is especially true of the use of the term "liberal". Stateside, Goldberg's title is provocative oxymoron; here it's flat-out contradiction. There, "liberal" is regularly used by conservatives to abuse anyone left of Paul Wolfowitz. In Britain, it has no such force: here, liberalism is underscored by Mill's principle of liberty, whereby the only purpose for which power can be rightfully exercised over any member of a civilised community, against his will, is to prevent harm to others. There are problems with the principle, but it can offer a bulwark against just those forms of totalitarianism Goldberg indicts and which he suggests were foundational for modern American liberalism.

Mussolini and Hitler didn't dig Mill. And yet, for Goldberg's thesis to make sense in Britain, they would have to. His book, as published here, is a triumph of the terminological will whereby words mean just what the author means them to. It was actually a Briton, HG Wells, who coined the term "liberal fascism". In 1932, Wells told Young Liberals in Oxford that piecemeal Fabian socialism and parliamentary democracy had failed to deliver, so should be scrapped. "I am asking for liberal Fascisti, for enlightened Nazis," he said. What can we say about this other than that it was a then-deluded, now-forgotten speech, and that Wells would have done better to read more Mill? And yet Goldberg takes it as a key text for his own now-deluded, soon-to-be-forgotten thesis.

Goldberg is a Kantian conservative sceptical of leftwing ideas of human perfectibility. Indeed, he argues that all totalitarianisms - Hitlerism, fascism, communism, Hillary Clintonism - proceed from the same lie: that tyrannical leaders can realise the utopian dream of "creating a better world" (Goldberg's scare quotes), and that when US liberals abuse conservatives as fascists for the usual things (opposing abortion and stem cell research, defending marriage and intelligent design), they don't know their history.

He insists we must recognise the "inconvenient truth" that communism and fascism were once bedfellows (forget that Hitler and Mussolini denounced and killed communists). In the 20s, US lefties detected no foul odour from Mussolini or Hitler, Goldberg argues. Fair enough, but I have a 1939 photograph of Lord Halifax and Neville Chamberlain flanking Mussolini at the Teatro dell'Opera di Roma - it wasn't just lefties who cosied up to fascists. He adds: "The horror of the Holocaust completely changed our view of fascism as uniquely evil." Fascism became a term of abuse, hung by liberals on conservatives like Goldberg. Goldberg's chief motivation is that this must stop.

Fascism, Goldberg contends, first appeared in government before Mussolini, thanks to the Democrat president Woodrow Wilson (whose first world war administration insisted that sauerkraut was renamed "liberty cabbage" in its cafeterias to reflect anti-German sentiment). Anyone who believes in collective action through the state to improve people's lives is fascist or operating with unconscious fascistic impulses, Goldman argues. Our 1944 Education Act and the NHS, then, rest on the same foundational principles as Kristallnacht and al-Qaida. Eugenics, cloning, Keynesianism, state-regulated abortion, the Führer (one chapter is called "Adolf Hitler: Man of the Left") all bear the same imprimatur.

Goldberg defines fascism as "a religion of the state. It assumes the organic unity of the body politic and longs for a national leader attuned to the will of the people." But this is hopeless: I long for Gordon Brown to be attuned to the will of the people, but I don't get religious about it. That there is in modern leftwing politics a religion of the state untempered by scepticism comes from Goldberg's nightmares rather than convincing political analysis.

"The promise of American life," Goldberg concludes, "will be frittered away for a bag of magic beans called security." There is nothing intrinsically wrong with security, except that, as Freud recognised, and as was demonstrated at Guantánamo, it's readily traded off for freedom.

What has this to do with the 44th US president? Goldberg notes that Barack Obama was trained by followers of the community organiser Saul Alinsky, whose "violent, non-confrontational rhetoric often sounded much like that heard from Horst Wessel or his Red Shirt adversaries in the streets of Berlin". It's a long journey from Horst Wessel to Obama, but Goldberg makes it histrionically short. Obama, surely, offers promise. It was his conservative predecessor, in the wake of 9/11, who frittered away the goodwill of the world.