Imagine the latest must-have item for kids was addictive and had a proven link with disrupted sleep, depression, low self-esteem and attempted suicide. You certainly wouldn’t buy one for your own offspring, but you might think banning it altogether was a step too far. That is, until your child comes home from school begging to have one, just like their friends.

You may not have to imagine much longer. There is increasing evidence that such a product already exists and is wildly popular. It’s called a smartphone. Perhaps the most persuasive evidence yet is a paper published last month in the journal Clinical Psychological Science, based on a study of more than half a million American adolescents over five years. A team led by the psychology professor Jean M Twenge found that kids who used their smartphones for three hours or more a day were one-third more likely to feel hopeless or consider suicide, rising to nearly half of those who used such devices for five or more hours a day. Simply using social media daily was linked with a 13% higher incidence of depressive symptoms.

If this finding is replicated, the new French ban on kids from using their mobile phones at school will not be criticised for being over the top, but for not going far enough. A compelling case for completely banning kids having smartphones is a handful of scientific studies away.

If a ban strikes you as draconian, perhaps you’re being swayed by status quo bias. When something has been established as normal, the suggestion that it is in fact terrible always seems outlandish at first. That’s why it took so long for people to accept that slavery was an abomination, that women deserve equal rights, that restrictions on tobacco were necessary. It also explains why so many of us continue to eat inhumanely reared meat without a second thought or buy cheap goods produced in the developing world by virtual (and sometimes actual) slaves.

If we had a new gadget and we knew it was very dangerous for children, we would never allow companies to sell it to them. So why should it be any different with an old gadget whose harms have only recently become apparent?

Any attempted ban would inevitably provoke protestations about the “nanny state”. But when a nation decides to ban something, it need not be a matter of the government imposing its will on the people, but of the people deciding to restrict their own individual freedoms for their own and the common good. Wearing a seatbelt is compulsory because we know it is a good idea and are happy for the law to enforce what we might be too lazy always to choose for ourselves. Smoking under the age of 18 is illegal in Britain because we know that it would be much harder to stop our own children starting a long, slow suicide if their friends were freely doing just that.

Another stock objection is that a ban would be unenforcable. So is the ban on murder. Laws don’t stop bad behaviour, they make it more difficult and more costly, and that is enough.

Some will protest that smartphones are not harmful in themselves and that, used properly, they can actually do a lot of good. That’s true, as it is of cars and motorbikes. But we know that letting kids get behind the wheel is bound to result in even more road carnage than we have already. If we also know that giving them smartphones will inevitably create many casualties, that is just as good a reason not to do so.

It’s not as though such a ban will deprive kids of the good things smartphones offer them. “Dumber” phones could give them contactability, a pocket camera, music on the go, maps if they get lost and GPS to find them.

They could also still use social media at home, of course, but without the excesses of constant connectivity. Some will still spend more time online than is good for them, but like all legal restrictions, a ban on smartphones would be an exercise in harm reduction, not harm elimination.

It could even be argued that we ought not to wait for conclusive evidence of harm to bring in such a ban. The precautionary principle suggests that if the risks seem high enough, a temporary ban until they are accurately calculated is perfectly sensible. If it turns out smartphones are not so problematic, we have hardly damaged our kids by depriving them of an iPhone. Most of us grew up without so much as a mobile and I doubt that’s the reason why we’re all so screwed up.

There may not be an obvious flaw in the argument – but still I struggle with the notion of such a ban. However, considering its merits does at least focus the mind on just how blind we could be to the damage being done to the next generation. Whether or not the full force of the law ought to be brought into play, the time for seriously considering restricting kids’ access to smartphones has surely come.

• Julian Baggini is a philosopher