Katharine Birbalsingh, headteacher of Michaela Community School, says the Black Lives Matter movement is a distraction. I think her claim is defensible - albeit because it raises an issue many of us would rather ignore.

The Times quotes her:

The problem with getting angry about racism is it's distracting. It leaves you with less energy to help you succeed, like working hard.

This alerts us to a nasty conflict - between beliefs that are true and those that are useful. It is true that black people face discrimination: for example, the ONS says that Black Britons earn 7.7 per cent less than their white counterparts even controlling for factors such as qualifications and occupation.

Telling Black pupils this is, however, not necessarily useful. It might demotivate them. Better instead to tell them that they can succeed if they work hard. Sure, even if they do so they'll face tougher lives than their white counterparts: they'll be less well-paid, more likely to be harassed by the police and more likely to face abuse, especially if they are women in the public eye. But it is likely that - on average - they'll have better lives if they take Ms Birbalsingh's advice than if they don't.

In this sense, Ms Birbalsingh is right. Racism is indeed distracting. Telling pupils about it is to tell the truth. But not all truths are helpful. We have a dilemma: do we tell young people the truth, or do we equip them to improve their lives? As Hayek put it in 1976:

It is...a real dilemma to what extent we ought to encourage in the young the belief that when they really try they will succeed, or should rather emphasize that inevitably some unworthy will succeed and some worthy fail. (Law, Legislation and Liberty, vol II, p74 in my copy)

This conflict between truth and utility isn't, of course, confined to what we tell children. We see it in other contexts. For example, people who overestimate their abilities are more likely to get good jobs than those with more truthful assessments of their skills. This doesn't always benefit them at the expense of the rest of us. It can sometimes be a social good, as Richard Nisbett and Lee Ross said:

We probably would have few novelists, actors or scientists if all potential aspirants to those careers took action based on a normatively justifiable probability of success. We might also have few new products, new medical procedures, new political movements or new scientific theories. (Human Inference: Strategies and Shortcomings of Social Judgment)

Similarly, whilst many of you might think religious belief false, it is useful in the double sense of making people happier and more resilient in the face of bad fortune.

And as Donald Davidson wrote:

Both self-deception and wishful thinking are often benign. It is neither surprising nor on the whole bad that people think better of their friends and families than a clear-eyed survey of the evidence would justify. Learning is probably more often encouraged than not by parents and teachers who over-rate the intelligence of their wards. Spouses often keep things on an even keel by ignoring or overlooking the lipstick on the collar. ("Deception and division", in Jon Elster (ed), The Multiple Self).

Untruths, then, can be useful in many contexts. Ms Birbalsingh's attitude to racism is thus justifiable - at least for someone in her position.

But, but, but. Isn't the purpose of education to tell people the truth? The truth, as Rawls said, is the first virtue of systems of thought.

Such a view is naïve. In a capitalist society, the function of schools is not primarily to impart rationality and knowledge. It is to habituate pupils into the ways of capitalism. Schools are, as Louis Althusser said, part of the ideological state apparatus. Within this function, talk of racism is indeed a distraction.