This isn't politics anymore. It's pathology. Imagine that someone you knew – a friend or a member of your family – was constantly uttering the words that are now commonplace assumptions in our national discourse:

"I am to blame for the sins of my grandparents and great grandparents. I must destroy or deny anything that I inherited from them – even my attitudes and opinions – because they are part of the injustice that was passed on. I must renounce whatever gives me an advantage over the less fortunate and accept that the colour of my skin is an indelible sign of my guilt." How might you respond to this?

I would guess that in the first instance you would try gently to reassure. You could say that while these obsessive feelings of personal guilt were well meant, they were unrealistic and self-destructive. If that counselling failed, you would probably call in psychiatric help because this behaviour had to be an indication of delusion and depression.

I am not being sarcastic. There is something deeply disturbing in the self-flagellating moral assumptions which are now so entrenched in official social policy that they are scarcely questioned – at least, until some event brings their consequences into such horrifying focus that the discussion can no longer be avoided. We seem to have reached that point.

How exactly did this metaphysical doctrine of original sin, or universal guilt, become so entrenched in what is assumed to be a scientifically rational, secular society? That is too big a question to take on here, but perhaps it is worth considering that the absence of religion, with its acceptance of human imperfection and the need for atonement, might have produced a vacuum that needed to be filled.

At any rate, here we are. The take over of our public institutions by this perverse ideology has arrived at what now seems clearly to have been its inevitable conclusion. The presumptions of innocence and guilt that are attached to racial identity by official government policy have culminated in the hideous death of an innocent young man.

The vivid recorded evidence for this was made public as a result of an extraordinarily courageous decision by Henry Nowak's own family. What it revealed was a degree of contempt for a person whose social category (his skin colour) made his pleas for help inherently suspect and beneath consideration. There is no ambiguity or room for doubt about this. The police, it was said in their defence, were not directly responsible for the death. By the time they arrived, it was too late. But that is not the issue.

What was shocking was their assumption that he was not to be believed. It is important to note that what is happening here is more than inverted racism: it is technically irrational, a form of cultural nervous breakdown. 

So total is the absorption in this vendetta against those who are tainted by a great inherited sin that the most sacred principles of our modern political system can be repudiated: that everyone is equal in the eyes of the law, and that any individual is innocent until proven guilty. All that has gone – extinguished in the name of a superior righteousness which attributes mass guilt to people as yet unborn.

I repeat: this is not simply unjust, or even ill judged. It is absolutely, downright insane. Rational people do not think like this, not about themselves or about their society. Not unless they are actually involved in a dedicated campaign to undermine that society.

This does remind me of the revolutionary Left's tactic designed to destroy faith in Western democracy by making it behave in blatantly repressive ways. You provoked the authorities into a violent crackdown so as to reveal the iron fist supposedly concealed under the velvet glove of liberal freedom. That technique was remarkably successful in the early days of the New Left when it served to demonstrate the revolutionary movement's point that capitalist democracy was just tyranny in disguise.

You may argue that this is rather far-fetched. The attribution of historic guilt which every new generation must accept from its white European forebears may be fatuous or even dangerous (as we have just seen) but it is unlikely to be part of some systematic plot to undermine democracy. 

But even if that is, strictly speaking, correct, it is certainly the case that its techniques are descended from the subversive school of gradual revolution. The objectives of that movement were to sow revulsion and alienation from the traditions of your own country: to encourage dissidence and rebellion against what had been accepted authority.

Perhaps this is just an accident of history: a mistaken attempt to improve democratic governance rather than overturn it. Maybe, with luck and perseverance, we can still correct that mistake. But only if the attempt to do so is not sabotaged by a mob of anarchic wreckers who are happily playing into the hands of the plotters (if that is what they are) against civic order. 

If there were an intention to create divisiveness and social collapse – or even to simulate it for politically opportunistic reasons – then the people who are calling out for revenge and chaos in the streets are behaving exactly according to plan.

They are playing their part in the dismantling of fair-minded rules, of genuine tolerance and reasoned argument: the principles on which this country prides itself. To cry for public "rage" (as opposed to legitimate "outrage") and incite retaliation is to abandon the only possibility that exists for defeating this absurd dogma. We need more rationality, not less. Less noise, more sound argument. Less division, more genuine debate on how this can be put right.

Expose the obviously ridiculous idea that because a form of words is perceived as racist, they must actually be racist, which undermines the whole concept of objective reality. If things must always be whatever they are perceived as being, there is no check on delusional or irrational thinking.

This is about so much more than policing. It is either mass derangement or ideology posing as neurosis. It can only be countered by rational people who insist on behaving responsibly.