THERE is a recurring theme in liberal thought — seeing some dark and nasty ideas in circulation, then blaming this on social media.

Somehow, the same ideas circulating in mainstream media, with solid backing from “respectable” voices, get missed. So obscure social media figures called “@TallDave100” get singled out as the voice of evil, while pundits with a place on BBC talk shows or columns in the Times can say exactly the same thing with more authority and be indulged by the “commentariat.”

Take, for example, the Great Replacement theory. This is what the New York Times describes as “a racist and misogynistic conspiracy theory that holds that white people face existential decline, even extinction, because of rising immigration in the West and falling birth rates among white women.”

The grand name Great Replacement was invented by French novelist turned right-wing ideologue Renaud Camus in the 2000s. But it is a variation on an old theme about migrants “taking over” our society.

The Great Replacement has become the ideology of both new fascist movements like Generation Identity and violent racist terrorists: in 2019, Brenton Tarrant shot dead 51 men, women and children at two mosques in Auckland, New Zealand — and his rambling “manifesto” was also titled the Great Replacement. Its one consistent idea was the fear of “non-white” people — obviously meaning Muslims, but also Jewish and Roma people and anyone from Africa or India — “replacing” white people and “their culture” thanks to immigration, “higher birth rates” and “decadent” culture in the West. Other mass shooters have also released Great Replacement-inspired manifestos.

The Great Replacement theory has been described as being “popularised by far-right social media personalities who populate the darker corners of YouTube, Reddit, Gab and even Twitter” — but its strength is its place in the mainstream. You don’t need to go to the “dark corners of the internet” —you can go to WH Smith’s or turn on the telly or radio.

Keir Starmer was recently criticised for failing to push back at Great Replacement claims when he appeared on an LBC radio phone-in. A caller, identified as “Gemma from Cambridge” backed Millwall football supporters booing at players kneeling in support of Black Lives Matter, “because,” she said, “if anything, the racial inequality is now against the indigenous people of Britain, because we are set to become a minority by 2066.”

It wasn’t a great moment for Starmer, who failed to recognise or challenge the absurd but dangerous “minority by 2066” claim. But it was worse for host Nick Ferrari and LBC radio: why were they so happy to give airtime to ”Gemma from Cambridge,” who is in fact was a yoga teacher, part-time musician — and an activist for new fascist party Patriotic Alternative, promoting Great Replacement theories under an assumed name. LBC had actually sought out “Gemma” to put her against the Labour leader, seeing these racist themes as either “good radio” or simply good ideas that it believes in.

But the Great Replacement goes much more mainstream than ushering its supporters onto talk radio for a bit of racist “controversy.”

Douglas Murray is a regular contributor to the Spectator, where he is associate editor, a Telegraph columnist, an occasional contributor to the Times and Mail and a regular figure on BBC political shows. However, his 2017 book The Strange Death of Europe is overtly a Great Replacement book.

Murray’s theme is that “the civilisation we know as Europe is in the process of committing suicide” because “continuing immigration and higher birth rates” of Muslim populations is overwhelming the “native population.”

His book promotes both older and newer anti-immigrant diatribes — he has a long section praising Enoch Powell’s Rivers of Blood speech.

Murray cobbles together other racist rants in a sort of “greatest hits” of prejudice — he has a lot of positive words about Oriana Fallaci, the Italian journalist who, in her version of the Great Replacement argument, complained that  Muslims “breed like rats.”

Murray has himself also been playing this tune for a long time. In 2006, he gave a high-profile speech in which he complained: “No European country's Muslim population is currently higher than 10 per cent — which ordinarily would be all right — not ideal, but all right. What makes it a problem is not only that native European birth rates are falling but that Western relativists are acting as a megaphone for the Muslim minority, making the volume of that minority exponentially greater and more threatening.”

Murray argued then that “all immigration into Europe from Muslim countries must stop” and “conditions for Muslims in Europe must be made harder across the board.”

So here is a best-selling book by a man with a history of bigoted speeches promoting the Great Replacement idea that drives racists across the world. Did it stay on the fringe? Not at all. Murray’s book has been reviewed positively in the Times — repeatedly. “A brilliant, important and profoundly depressing book,” read one; it was “courageous and articulate” in a second — and a “tremendous and shattering book,” according to a third.

The Telegraph also backed the theme, arguing that Murray’s “overall thesis, that a guilt-driven and exhausted Europe is playing fast and loose with its precious modern values by embracing migration on such a scale, is hard to refute.”

A book that suggests that Muslims are trying to “outbreed Europeans” and will overwhelm “decadent” Europe and that Powell’s racist speech predicted the future is treated as a brilliant, sophisticated work.

There is no need to look for hard-right ideas in on the shadowy fringes, they are in the bookshops, in the newsagents and on our screens. They are put there by our leading editors and publishers.

The liberal pretence that these nasty ideas mostly come from outside the mainstream media is a displacement activity, because leading commentators don’t want to get in an argument with the editors and owners who give them jobs. But pretending that our leading newspapers and magazines don’t promote prejudice also means that we don’t properly fight it.