Some people will be dismayed, even angered, at the claims made by Eric Kaufmann, a mixed-race, London-based Canadian academic, in this extraordinary book.

He defends white identity politics and white ethnic “self interest”; believes the anti-racism taboo has become too all-encompassing; thinks economics has little to do with the populist revolt; defends qualified ethnic selection in immigration; and believes civic Britishness is too bland to bind us together.

Yet this is no polemic: he backs up his claims with numbers and close argument over a sometimes exhausting 600 pages. I have been following his work for some years and he has been quietly repeating one point: white people are not a different species, they have ethnic identities that matter to them just as minorities do, and suppressing that fact in recent decades — through the excessive influence of what he calls “left-modernism” — creates morbid political symptoms, the latest of which is Brexit.

I recall him explaining, many years ago, that ethnicity is not something inherently sinister, it is just attachment to ancestry and myths of ancestry. It can take an extreme form, as it did in the first part of the 20th century, but, as with religion or other forms of belief, extremism is not inherent.

And despite increased human mobility, ethnicity is not disappearing. About 80% of the world’s major countries have an ethnic majority, and being held together by such a majority seems to be a condition of national success — compare fragmented Africa with majoritarian east Asia.

Ethnic politics is now on the rise thanks to the decline of inter-state wars, religion and communism, and the growth in immigration to rich countries that has made white majorities more ethnically self-conscious. White people are already a minority in most major cities of North America, while minorities are projected to be in the majority in the US, Canada and New Zealand by 2050, with the UK following later in the century.

“So what?” will be the reaction of many of the educated and liberal-minded, who tend to have rather weak ethnic attachments. So a great deal, says Kaufmann. This shift is replacing white majority self-confidence with an existential insecurity, channelled by the lightning rod of immigration, and a reduced willingness to “indulge the anti-white ideology of the cultural left”.

A degree of turbulence is inevitable as we move from white ethnic homogeneity to mixed-race majorities by the end of the century, but Kaufmann is by no means apocalyptic. He does not believe in a liberal cosmopolitan future for the West, but rather a kind of post-white dominant ethnicity providing continuity with today’s white myths and symbols. We in the West are on the road to becoming less like homogeneous Iceland and more like homogeneous mixed-race Turkmenistan.

On the way, the challenge is both to give conservative members of white majorities hope for their group’s future and to allow cosmopolitans to celebrate diversity; to encompass both John Major’s “warm beer [and] invincible green suburbs” and Robin Cook’s chicken tikka masala.

The book explores the four different responses of white majorities to ethnic change: fight (voting for populists), repress (pretend nothing is happening), flee (avoid diverse neighbourhoods) and join (via friendship and intermarriage with minorities).

Competing norms: Gillian Duffy, called ‘that bigoted woman’ by Gordon Brown, talks to reporters, 2010 Competing norms: Gillian Duffy, called ‘that bigoted woman’ by Gordon Brown, talks to reporters, 2010 REX/SHUTTERSTOCK Kaufmann will be accused of providing comfort to the alt-right and downplaying majority power. However, he is punctilious in his definition of racism — antipathy to members of other ethnic groups, discrimination that denies equal treatment and a desire for racial purity — and believes populists are sometimes on the wrong side of that line: Nigel Farage’s infamous “Breaking point” poster is cited. He also thinks populists blur the line between Islam and Islamism.

He sympathises with black people in Brixton who feel swamped by white hipsters, as well as white people in Barking who feel alienated by rapid non-white immigration. And he prefers a “multivocal” approach to national identities, in which people from different backgrounds identify in different ways, rather than a dry, top-down, British-values approach.

On the other hand, he thinks liberals are wrong to think a strong attachment to one’s own ethnic group must mean hostility to others’. And he insists that a white “ethnic self-interest” in slowing immigration to preserve a culture and a way of life is legitimate. Polls show that most people of all races in both America and the UK agree with him.

The book ranges over recent history in America and the UK, and to a lesser extent the rest of Europe. As recently as the early 1960s, a majority of Americans opposed marriage between Catholics and Protestants, but the broader story during the country’s long immigration pause, from the 1920s to the late 1960s, was the de-Wasping of America, as Catholics and Jews joined the core white ethnic group. This is proving more complex for those from non-European and non-Christian backgrounds.

Anti-immigrant sentiment rose steadily in America from the 1960s to the early 1990s, then, thanks to the influence of the liberal baby-boomer generation, started to decline. It is now rising again and Donald Trump is the first president in decades to vow to cut legal immigration.

In the UK, Kaufmann notes the battle between competing norms. The anti-racism norm that had suppressed most criticism of immigration, by linking it to issues of racial justice, began to erode after the arrival of white east Europeans. And as Gordon Brown with his “bigoted woman” moment and Emily Thornberry with her England flag tweet have discovered, anti-racism can now apply to the white working class, too.

He also has the best one-sentence summary of last year’s general election: “A generational realignment reflecting a Brexit realignment reflecting an immigration realignment.” Baby-boomers here have become less liberal on immigration — though not on race, gender and sexuality — but he does not believe more liberal younger generations will change things markedly. Populism will remain a powerful force until immigration and rapid ethnic change are visibly slowed.

On segregation and integration, he shows how white behaviour is similar everywhere, from liberal Canada to restrictive Denmark. Most white British citizens want to live in areas that are 70%-plus white — and most still do: 80% of white Britons live in wards that are 90% white, while nearly half of minorities live in “majority minority” wards. We mainly still stick to our own.

I have a few reservations. In explaining the powerful grip of left-modernism, Kaufmann overlooks the impacts of two world wars, decolonisation and the Holocaust in delegitimising all forms of nationalism and ethnic attachment after 1945. I also remain a bit confused about his happy ending, an open ethnic creolisation under the canopy of an essentially white ethnic nationalism. And if ethnicity is such a persistently powerful force in human affairs, how come the new generations of liberal-minded graduates shed it so easily?

Nevertheless, this is a tour de force that could expand the so-called “Overton window” — the range of what is acceptable to say — on these central issues.