HOW should the European Union manage its multilingualism? The 28 partner countries speak an unwieldy 23 languages. To enable more shared modes of expression, Johnson's most recent column proposed that every child in Europe should learn at least two foreign languages. "Nonsense", replied quite a few commenters. Many argued that it would be far more practical if all European matters were simply conducted in English. Why not let the most popular language spread to every corner of Europe—and, indeed, the rest of the world?

This would certainly seem more practical than teaching every European child two more languages. But mandating English might also serve to undermine loyalty to the EU. There are too many Europeans who would rather not have English dominate political affairs. The continent has more native German-speakers, including four countries where German is an official language. French has as many native-speakers in Europe, too, and is official in three countries (not to mention Europe's de facto capital, Brussels). Native English-speakers make up less than a fifth of the EU's population. And, awkwardly, English is the official language of the one country that will soon hold a referendum on whether to quit the EU entirely.

But the real reason not to adopt a "mainly English" language policy involves the EU's promise to its members, under the official motto "united in diversity". No country joined the union in order to be crushed under a homogenising wheel. Important laws are made at the EU level, and Europeans have a right to be able to understand them. This includes not only grasping the final laws, but also the debates in the European Parliament. The EU already makes big gestures to small countries (like giving Malta and Germany the same vote at the European Central Bank). Encouraging multilingualism, not just fluency in English, seems a more sensible way of showing that all countries matter.

Recognising the importance of all languages big and small may seem romantic. But when it comes to arguments about language, as with trade, emotion often trumps reason. Hard facts may be a good reason to, say, shut an old steel mill that cannot withstand competition. But a language is not a steel mill. There is far more at stake: not just people's livelihoods, but their identities and cultural diversity itself. The continent's proliferating anti-EU parties would throw themselves a party if the EU foolishly tossed aside national exceptionalism for an English hegemony.

Telling 26 of 28 EU countries that of course they can keep their cute little languages, but that all serious stuff (business, academic work, legislating) must be done in English, is asking them to accept second-class linguistic citizenship. Languages that are not used for science or business fail to develop the up-to-date vocabulary and style needed to do so. Over time, if neglected, they shrink to fewer and fewer domains. In the long run, they may be spoken only at home or between intimates, like Swiss German or Scottish Gaelic. Already today, in liberal and pro-American countries where English ability is outstanding, like Denmark or the Netherlands, people fear that their languages are considered fit for fewer and fewer arenas. Populist and xenophobic parties, the kind that say Europe tramples on national uniqueness, play on this fear.

It would be far better to encourage every European schoolchild to learn a second foreign language after English. It could be a big one, like German, for work reasons. (This would help European labour mobility, a big shortcoming in the single market.) It could also be a neighbouring language for cultural reasons, which would help Europeans cross borders and build the kind of intimate relationships that build fellow-feeling and gradually push Europe's old enmities further into the past. It isn't easy or cheap, but already in some multilingual countries (like Luxembourg) three languages are expected for national cohesion. Europe is wealthy enough to devote some of its resources to that charming idea of unity in diversity.

The French have a law stating that if public signage is translated into another language, it must be into at least two other languages. This handily prevents English from dominating French signage. French chauvinism is at its worst when it attempts to ban or shame English words out of the public eye. But the country's approach to translating signs is not a bad one, and not a bad model for wider thinking about language. It is inclusive, even expansive. It is a grand idea for people to learn English. It is even grander to learn English and something else too.