One Saturday morning, I took my 5-year-old son to the playground. A few minutes into his “ninja training” regimen, he attracted a fan. The other boy was younger, but the plastic glint of my son’s dollar-store sword slicing evil from the air proved irresistible. He edged closer and mimicked his moves, until they began to play together, shouting “Ya!” in unison, kicking with the verve of Rockettes. I smiled at the child’s father on the next bench and made an effort at playground banter, asking the boy’s age and whether they lived nearby. But after a few half-answers he pointed to the AirPods in his ears.

What could I do?

I picked up my phone and scrolled through the news. A fast-casual restaurant chain was experimenting with replacing its cashiers with “virtual cashiers” connected by video link from Nicaragua and paid around $3 an hour. As I sat there, willingly ignoring and being ignored by the only other adult nearby, the story struck me as just another example of how modern life keeps us insulated from strangers.

Not so long ago, it was impossible to go through life without speaking, in some way, to a variety of strangers in your life: The bus driver, barista, security guard, receptionist, butcher, government clerk, store cashier and restaurant server were all humans who required at least the bare minimum of conversation. If you were at a playground a generation ago, halfheartedly watching some swing-set drama, ignoring the casual greetings of another parent would be extremely rude

It shouldn’t be this way. Engagement with strangers is at the core of our social contract. Most religious faiths instruct us to welcome the strangers we encounter, and there’s good reason for this. If we engaged only with the people we knew, our world would be small. That leap of faith toward the unknown other is what allows us to grow beyond the family unit, tribe or nation. Everyone you converse with who is not a biological relative — your best friend, neighbor, lover, spouse or even that chatty taxi driver from last weekend — was a stranger before you spoke to that person. Anytime we ignore strangers in our vicinity, whether because of fear, bigotry or the everyday convenience and efficiency of digital technology, we weaken that contract.

Far from random human inconveniences, strangers are actually one of the richest and most important resources we have. They connect us to the community, teach us empathy, build civility and are full of surprise and potentially wonder.

“I’ve spent many years studying the people who are the furthest out of our social networks, and they really do add a richness to our life that we miss when we’re not there,” said Gillian Sandstrom, a senior lecturer at the University of Essex, whose research has demonstrated how the small, transactional relationships we create by talking to strangers are important pillars of our social and emotional well-being.

“We have all these kinds of people who populate our lives, who we aren’t that close to and we don’t share our deepest, darkest secrets with,” said Dr. Sandstrom, who forces herself to speak to strangers every day, despite identifying as an

A study published last fall showed that despite our fears of awkwardness, deep, meaningful conversations with strangers are not only easier than expected but also left participants feeling better about themselves.

In some ways, our recent aversion to strangers is a byproduct of technological evolution. Sure, newspapers and magazines, cassette players and televisions were all potential distractions, but none of them fully normalized ignoring other people in the way that smartphones have. E-commerce sites and third-party restaurant delivery apps incentivize us against entering stores and restaurants filled with strangers. Some digital technology goes further, like the Uber feature that allows you to preemptively mute a driver’s attempt at friendly conversation.

Then came the pandemic, and suddenly, each physical encounter with a stranger carried the potential of death. We were ordered to stay home, avoid public spaces and speak only within our trusted bubbles. We sought refuge in the distance that digital technology allowed us, watching movies, attending exercise classes and having meetings all without entering a theater, gym or office. The longer we hid inside, the fewer strangers we encountered. Our world grew inward and suspicious, our fears exacerbated by the latest news about fresh variants and rising crime rates not seen in decades. “Stranger danger,” that discredited catchphrase of the milk-carton/unmarked-van kidnapping past, seemed to creep back into our present.

Strangers are intimidating for a reason. Even when they are not physically threatening, they can make us feel uneasy, inhabiting awkward silences. Digital technology promises to fill those silences with more hardware and software to insulate us from those we do not know, like the robo-barista vending machine that opened near me last year, which serves lattes through a little window with nary a syllable of chit or chat.

But a future where coffee is served by robots is not an improvement on the coffee shop. It ignores a central purpose of the neighborhood cafe, a place for hot drinks and human interaction.

At the playground, I glanced up from my phone and saw my son and the other boy yammering away as if they’d known each other for years. The other father looked up too and seemed genuinely surprised at this instant relationship. He walked over, knelt and asked his son who he was playing with.

“I don’t know his name,” the boy said, as his tiny fingers clutched one of my son’s Lego figures, “but he’s my friend.”

David Sax is the author of the forthcoming book The Future Is Analog: How to Create a More Human World.