After the Cologne sex attacks and the media’s downplaying of the issue, perhaps the most telling comments came from Ralf Jaeger, interior minister for North Rhine-Westphalia, who said: ‘What happens on right-wing platforms & chat rooms is at least as awful as the acts of those assaulting the women. This is poisoning the climate of our society.’

Lots of people in positions of power in western Europe are terrified of a Right-wing backlash against immigration; some perhaps genuinely fear a new Holocaust, others maybe use it as an opportunity to push the Overton Window. Who can tell, but Mr Jaeger’s comments show how irrational this mindset is. Taking aside the fact that it is more likely to be the importation of 1m+ people from very difficult cultures, rather than the response to it, that is threatening the social climate: not only is it morally bizarre to equate Right-wing chat rooms to sexual assault, but if your obsession with the Right causes you to downplay or ignore major social problems that results from multiculturalism, then surely you are more likely to cause Right-wing extremism?

This is what I wrote in the final chapter of my depressing book about this mindset, and the Greek tragedy it is bringing about:

For those who experience disconfirmation, the realisation that an idea on which they banked their entire moral framework, and their country’s future, is completely misguided is difficult to take; similar to the sickening feeling of finding out that the plausible young man might not actually be the son of the deposed president of Gabon and doesn’t really have US $26 million in the bank. This may partly explain the exaggerated outrage which people show towards any critic of diversity; often people who have advocated mass immigration all along can only respond to criticism by angrily asking what the critic might do, the alternative being presumably mass deportations or mass murder. Yet if it was the proposed alternatives they feared all along, why did they pretend there was no problem? It is a telling response and something one would not expect of a view based on rational analysis, rather than faith. Instead it looks like a subconscious admission that the experiment has left Britain with deep problems.

One strange aspect of the debate is that believers often talk of diversity as being inevitable; yet when people say something is inevitable, it suggests that their enthusiasm is not entirely genuine. ‘Inevitable’ was the line Bolsheviks used about Communism, and by Euro-federalists to describe their dream of a nation-free Europe. Nothing is inevitable except death – our future may be secular or religious, conservative or liberal, capitalist or socialist, and there is simply no unstoppable one-way direction towards the end of history. One should be wary of any argument that uses the line.

People also talk of the achievements of a multiracial society in the same way they talk about a community overcoming a serious disaster. We’ve got through; we’ve survived; there haven’t been mass casualties. People do not normally talk about good things in this way. Where they do discuss it, it is couched in euphemism; for example the Wikipedia page on ‘diversity in the workplace’ poses opposite sides of the argument as ‘positives’ and ‘challenges’. And even when promoting diversity, its advocates talk about it in the same language they would about a disability; the calls for American colleges to be ranked according to ‘diversity’ alongside such standard measurements as exam results looks like a subliminal admission that it is a liability, like counting the number of children eligible for free meals.

Because the case for mass immigration is so weak, the argument often turns instead to the individual. Supporters base their argument on other people’s supposed fears, of immigrants and immigration, change or globalisation. To be in favour of diversity is to be positive, optimistic, courageous and decent; to be against implies fearfulness, resentment or hostility. Yet hostility to diversity does not mean hostility to foreigners, and most opponents are clearly not hateful in the slightest. The Pew Foundation’s wide-ranging research in 47 countries showed that opposition towards immigration was universally strong, yet significant majorities of people in England, France, Canada and the US had positive attitudes to third world peoples. In the words of Labour peer Maurice Glasman, most people are anti- immigration, but pro-immigrant.

Change is not necessarily positive or negative, yet change for change’s sake is exactly the argument used for demographic revolution; that because older and less attractive people are fearful of and hostile to change, we should embrace it. This is not an argument one would present to a climatologist, for instance (and a graph of immigration levels looks far more like a ‘hockey stick’ than its climatic equivalent) yet any rapid change to the social ecosystem is bound to have unpredictable results. But for all the psychological analysis of opponents’ motivations, proponents consistently run away from this central question – do the benefits outweigh the costs?

Diversity came with the best intentions, but beyond a certain degree of immigration the costs to a society, in terms of greater atomisation, inequality, crime, religious tension, government interference and authoritarianism, easily outweigh the benefits. It is a utopian idea: we are not going to start sharing our nations with the rest of humanity anymore than we would share our property, and those who fall below the high moral standards set by the Jacobins of diversity are not deviants. Until this is appreciated England will continue to see mass immigration as a solution to various economic problems that are actually aggravated by immigration, like a delusional hypothermia sufferer taking off his clothes.

The sceptics may be wrong, of course. It is perfectly possible that we may look back at this change and see it as a positive development, but it will not be accepted either way until there is an actual debate. Sixty years after mass immigration began, and ten after it intensified, we have not plucked up the courage to ask – has the cost been worth it?

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And we have not asked because we are scared of what the answer will be, and of the consequences. Yet there is no reason to be fearful; perhaps it is because we are past the stage where the children of immigrants fear the spectre of repatriation that we can discuss it more openly. Honest debate need not lead, in the words of Woody Allen, to black-and-white newsreel footage scored by a cello in a minor key. In light of the Holocaust, and the various other atrocities carried out in the name of nation or race, it is understandable why Western societies feel so tortured about immigration, but it is only the West that is so tormented. And while a world free of ethnic conflict is a worthy goal, the mass importation of peoples across continents is a strange way to achieve it. It is paradoxical that those who cite the spectre of racial conflict are justifying a policy most likely to bring it about – mass immigration; like Oedipus, western Europe is, by trying to avoid a disastrous future, doing everything to make it happen.

Alain Finkielkraut, a French essayist whose father was deported to Auschwitz, has warned how anti-racism is the biggest danger facing the West. ‘The lofty idea of “the war on racism,”’ he has said: ‘is gradually turning into a hideously false ideology. And this anti-racism will be for the twenty-first century what Communism was for the twentieth century: a source of violence.’ Just as the pacifism that followed the horror of the trenches led the way to the even worse inhumanity of Hitler’s war, so Britain and its European neighbours, in recoiling from the idea of nations, may now be paving the way for fresh disaster.

Our inability to distinguish between pathological racism on the one hand and a desire to protect national integrity – a desire we would not dream of denying any non-Europeans – has significantly diminished our quality of life and promises future problems. And in what area of life, political or otherwise, do we even question the wisdom of honestly discussing an issue? Only when it has become a taboo in the most Freudian sense, something we dare not think about for fear of what we might feel. Every society needs taboos, but as a result we have become terrified of expressing opposition to enormous, dubious change in case we are classed as morally abnormal.