Why does virtue-signalling matter? It’s a fair question. After all, if people display virtuous behaviour, need we care about their motivation? I understand why some are irritated by the term; deployed unsparingly, it can be used to denigrate any act of decency.

Yet, if the phrase is relatively new, the concept isn’t. Several of the best-known passages of the New Testament (The Widow’s Mite; the Sermon on the Mount) deal with the contrast between sincere acts of virtue and those driven by self-advertisement.

Why is this distinction important? For one thing, cheap displays of virtue may crowd out more concrete actions. Woke discourse largely dodges practical and economic questions in favour of increasingly arcane etymological point-scoring and shaming. Worthwhile causes are hijacked by middle-class activists who use them to play status games against other white people they dislike, often through extravagant displays of what Robert Henderson calls ‘luxury beliefs’. Such signalling wars can be highly counterproductive. No chant from a football crowd has ever converted anyone in the opposition stands. I sometimes wonder whether modern facepaint was secretly invented by the CIA in the 1970s to discredit CND.

A few people in the Remain movement understood this risk, incidentally. They turned up in Parliament Square flying both a Union Flag and a European flag. They were a minority.

But another reason purist signalling behaviours should alarm us is that they inspire only a narrow set of ideo-logically conformist policies. There is often a gulf between what you can do to show you care about any problem and what you might do to solve it. You signal that you care about problems only with direct actions, whereasreal-life problems are often solved obliquely. (I recently asked someone in the insurance industry what had been the most important event for home insurers over the past few decades. ‘Oh, without doubt, the invention of oven chips,’ he replied.)

In physics there is a famous exam question: ‘Show how it is possible to determine the height of a tall building with the aid of a barometer.’ The examiner’s dilemma arose when one candidate proposed perfectly valid solutions which did not show the required understanding of physics.‘Attach the barometer to a piece of string and hang it off the top of the building. Length of string plus length of barometer equals height of building.’ ‘Throw the barometer off the building and measure how long it takes to hit the ground; using the equation h=1/2gt² you can calculate the vertical distance travelled.’ Other solutions included, perhaps best of all, going to the architect of the building and saying: ‘If you tell me how tall the building is, I’ll give you this nice barometer.’

One often overlooked point about this question is that the ‘approved’ answer — which involves comparing air pressure at the top and bottom of the building — is a terrible way of ascertaining the height of a structure. If it is a one-storey building, it is far, far worse than guesswork; even if it is 100 storeys high, unless you correct for air temperature, you risk being out in either direction by 40 per cent.

One of the problems of signalling in politics (and business, too, where reciting MBA twaddle is increasingly becoming a career requirement) is that, like that physics question, the ideological purity of your proposed solution — your ability to signal approved cleverness and navigate social shibboleths — is more important to your status than the quality of your output. Showing you’re good is not the same as doing good.

Harry Truman clearly spotted the signalling problem: ‘Anything is possible,’ he once said, ‘just so long as you don’t care who gets the credit.’