A 14-year-old has no more constitutional right to use Instagram than she has a constitutional right to purchase a fifth of Hennessy, and strong limits on teenage access to various substances and products are a normal feature of liberal society — opposed primarily by the kind of libertarian who identifies forever with his 13-year-old self.

That libertarian’s argument, in this case, boils down to the idea that if you have a novel, obviously addictive technology that might well be associated with depression, narcissism and self-harm, you need to wait for absolute certainty in that association before you start thinking about limits on how kids use it, because once upon a time there was a moral panic about comic books and wasn’t that embarrassing. Perhaps I’ve buried my own 13-year-old self too deeply, but I am not convinced.

But if we are willing to think about imposing limits on the teenage Instagram experience, then we probably need something more than a general rage at Silicon Valley’s reckless nerds. Yes, it would be ideal if social media companies would self-regulate in their relationship to teenagers, and it’s swell that in the wake of the bad Wall Street Journal publicity Facebook is temporarily putting a hold on its plans to start a version of Instagram explicitly for kids. But real, sustained self-regulation generally happens only under threat of external action, or with the establishment of a new consensus around what’s acceptable to sell to kids. So for people who read the Journal article and come away irate at Facebook, the question should be, what exact consensus do you want? What norms do you expect Instagram or any other company to follow? In the light of the data, what rules should they obey?