CITIZEN armies have been replaced in most countries by professional soldiers, who tend to do a better job of defending the nation than conscripted interns. But the draft is making a comeback in some surprising places. Sweden brought back military service this year, after an eight-year hiatus. France’s president, Emmanuel Macron, is planning to revive national service, which was abolished in 1997. Thinkers in America, Britain and elsewhere have floated the idea—and polls suggest that voters like it.

Some small countries with menacing neighbours, like Sweden and Lithuania, are resuming conscription for defensive purposes. But others have different motives. France, which will let teenagers work in a civil organisation rather than the armed forces if they prefer, hopes to foster social cohesion. This cuddlier sort of conscription is already popular in Scandinavia, and growing elsewhere. South Korea has announced plans for social service as an alternative to the military sort, following a court ruling in favour of conscientious objectors.

National service has much to recommend it. It creates a shared experience in otherwise fragmented societies, breaking down barriers of class, race and gender. It can be used to instil the values of a country in its population. It builds respect for the armed forces, teaching civilians that their freedom ultimately depends on others’ willingness to kill and be killed. And it subjects a pampered population to a bracing dose of spartan clean living, away from iPads and alcopops.

The odd thing is that this wonderful opportunity should be reserved only for the young. Age limits are understandable if the purpose of conscription is to repel marauding Russians. But it makes no sense when the aim is social cohesion. One of the greatest divides is generational; that will hardly heal if oldies sit out the experience. Targeting the young also means that immigrants, who might benefit most, miss out if they arrive as adults. As for the need to impart wholesome values, youngsters should not be the priority. In France, as elsewhere, the elderly are most in need of a refresher on the importance of égalité, at least when it comes to women, gays and Muslims. Older people also drink more and watch more TV. They are, in short, ripe for a few weeks a year of boot camp.

So why do countries with “socially cohesive” conscription not impose it on their entire population? The answer is embarrassingly obvious. Voters conclude, reasonably enough, that the benefit to society is not worth the cost to their personal liberty. State-mandated work is often used as a punishment, after all. It interrupts plans, breaks up families and has the potential to be colossally boring. Most polls find that national service is popular only among age groups that would not have to do it. If they believe that such an exercise is not worth their own time, they should not impose it on others.

Fraternité v liberté

The more liberal alternative is to expand the opportunities for voluntary service. America’s Peace Corps is one model. Britain’s Teach First scheme has got bright graduates into classrooms of their own free will. Other public services, including the armed forces, could increase the number of short-term placements, for all age groups. Doubtless Mr Macron, who sadly was just too young for the draft, would sign up like a shot.