So many of the worst nightmares of parenting start with a phone call: a child out of arm’s reach, not in the house, not in her bed. Or, in this case, a text on a rainy night from my daughter to my wife, who then relayed a command to me: go pick her up now. Instead of taking the subway to the Upper West Side, as I would have any other night, I got into my car and dashed up the West Side Highway. My daughter is in middle school; this was the first time she’d ever been to a nighttime party, at the house of a friend from school. A parent would be at home the whole time, we’d been told. How bad could it be?

“There was a boy making jokes about rape,” my daughter said, five minutes later, in the passenger seat. “We told him to shut the fuck up, but he wouldn’t, and my friend’s mom told her to try to work it out herself, which was completely unfair, and everyone was crying, and I just got tired of it, and I have a headache. That’s why I texted Mom.”

I take the blame for my daughter’s casual profanity. My wife is responsible for her emotional acuity. No one can say where she gets her unflappable, don’t-mess-with-me temperament. She is a chaos manager and an empath. But adolescence is a wet street, where skidding is likely and the car sometimes feels entirely weightless. Last summer, an older girl we knew of—a friend of friends—fell from a fire escape and died during a party. When I heard the news, I did the predictable thing: I measured the distance between my nearest child and this catastrophe. It felt very short. The pills in every parent’s medicine cabinet. A friend saying, “Oh, I know what this one does.” Another friend saying, “It’s no big deal, we go out there all the time, it’s just like having a balcony.”

“She did the right thing,” I said to my wife later. “She made the right decision and called us because she didn’t feel safe.” The unspoken question, hanging between us: What about the next time, and the next? And another question, more like a demand: Why can’t we be sure? We want to be sure.

In my junior year of high school, in 1992, I briefly convinced myself I was H.I.V.-positive. I had a low-grade fever, night sweats, chills, and a cough that lasted more than a month. I wasn’t wildly sexually active, though I’d had sex. My biggest fear, which magnified grotesquely the more I thought about it, was that I’d been exposed while working as a hospital volunteer in an emergency room when I was thirteen, in 1987. I’d handled bloody instruments once or twice, and I had been close to all manner of sick patients. Couldn’t that be enough? I read Hermann Hesse’s “Siddhartha” in English class, which convinced me that I was about to die and enter nirvana. (Don’t laugh.) I told no one. Finally, after weeks of the most intense worrying, I worked up the courage to go to my family doctor, explain the situation, and ask for an H.I.V. test.

If I were a teen-ager in 2019, I’m not sure I’d be able to keep that kind of secret. There probably are teen-agers out there who could face an existential fear without a single Internet search, without texting or posting or sharing, who could cover their tracks sufficiently to prevent a determined parent from snooping, but I haven’t met any. When I was seventeen, I didn’t have to decide whether or not to act like a media hermit, but I did have to decide whether or not to say anything out loud, and I chose not to. I needed to sort out the difference between fantasy, paranoia, and fact; when I couldn’t do it alone, I had to choose the kind of help I needed.

What does it mean for a child today to be alone, to have an independent inner life? I started wondering about this a few years ago—while my own kids were still enmeshed in Daniel Tiger and Rainbow Looms—over a weekend with friends who had two teen-age girls at home. Their house had a strict device-management system, where phones and iPads lived at a charging station in the kitchen and could only be “checked out” for short, approved periods. My friend C. sat with his daughter and thumbed through her text messages, reviewing them for content. You have to do that, he told me later. I’m not sure what particular danger we talked about, but it’s easy to list the possibilities: bullying, suicide talk, drug talk, stalkers, predators. There are secret texting apps and anonymous texting apps; there are chat forums and comment sections; there’s Twitch and Whisper and Kik, and, because I’m forty-four and not fourteen, surely many others that I haven’t heard about.

I’ve talked to scores of parents who use location-monitoring software to track their teen-agers’ movements, who scrutinize their Instagram feeds and photo streams, play the same online games, add themselves to group chats. A motivated parent can give their young driver a car that shuts off the radio, won’t go above a certain speed, and sends text alerts home if the car goes outside a pre-approved area. This is in addition to all the other ways children and teen-agers are no longer allowed to be left alone: over the last decade, dozens of American parents have been charged with criminal neglect for leaving their children in a car for a few minutes, or for letting them walk or ride bikes in their own neighborhoods. A movement for “free-range parenting” has pushed back against this culture of obsessive supervision, which also criminalizes the dilemmas faced by single parents, two-career parents, and parents who don’t earn enough to pay for constant childcare. Its leaders point out, among other things, that U.S. crime rates have fallen dramatically over the last twenty years, and it’s safer for children to be alone now than it was in the nineteen-seventies and eighties, when today’s parents were young.

As my children get older, I’m realizing how profoundly my instincts have been shaped by this culture of constant supervision, which wants to believe that it’s the same thing as intimacy. I still prefer it, over all, to the enormous distance that I sometimes felt as a teen-ager toward my parents. But I want to ask: Who is speaking up, today, for a young person’s right to a private life, to secrets, unshared thoughts, unmonitored conversations and relationships? Phrasing it this way sounds dangerous, and also counterintuitive: Don’t teen-agers and young adults today accept that technology is embedded in every aspect of their lives, that just being alive means being present (at least to some degree) online? My daughter, just coming into her own digital domain, certainly does: she has her own phone and laptop, ostensibly for homework, is allowed to text and chat with her friends, and desperately wants her own social-media accounts. Kids her age seem to accept, reluctantly, that the price of having a social life is having their parents one step away from everything they do, sharing the same accounts, playlists, search histories. We’re the ones who regulate her time online (and use the indispensable plug-in Freedom to keep her offline while she’s studying, just as we use it ourselves). When we notice an item that warrants a conversation—a questionable YouTube search, for example—we talk about it. At length. We’ve already had more family conversations on issues related to sex—sometimes in the form of extremely contemporary tangents, related to Cardi B’s taste in shoes or Stormy Daniels’s career choices—than I ever had with my parents.