Stranger Danger: An Economist's Guide To Overcoming Distrust

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"Don't talk to strangers," parents tell their kids. "Don't take candy from strangers." Many of us are taught at an early age to fear strangers. You know: stranger danger.

But living in society means having to trust random strangers every single day. You trust strangers when you eat a cheeseburger at a restaurant. You trust strangers when you put your money in the bank, or buy something online. You trust strangers to not swerve and kill you every time you drive on the highway.

A new book by Benjamin Ho, Why Trust Matters: An Economist's Guide to the Ties That Bind Us, argues the story of the economy — and all of human civilization, really — is the story of how we've evolved to trust larger and larger groups of strangers.

Human beings are social creatures. But our monkey brains are equipped to know and trust only a limited number of people. Around 150, according to the research of the British anthropologist and evolutionary psychologist Robin Dunbar. It's known as Dunbar's number. Dunbar argues it's why we see 150 as a standard number for infantry units of militaries throughout history, and even the upper limit of people we regularly interact with on Facebook.

The task of human civilization then, in Ho's telling, was to figure out how to get us to trust more than the 150 people our limited brains could really get to know. Societies did this by creating new institutions. Religions, for example, created group identities, norms, and beliefs that allowed people to trust fellow devotees. Governments created the rule of law, which gave us rules and some assurances that strangers couldn't just mess with us and get away with it. Entrepreneurs and companies figured out ways we could trust them by, for example, creating brand reputations. That McDonald's off the highway may be run by a bunch of strangers, but it's got the golden arches! We know what we're gonna get.

Humanity is constantly devising new ways to trust one another. Many of the multibillion-dollar companies created over the last couple decades have been built on new ways to overcome distrust. Lyft and Uber allow us to ride in strangers' cars. Airbnb allows us to stay in strangers' homes. We overcome our distrust by using social media avatars and reputation-building review systems to judge whether these strangers are sketchy or not. The main innovation of Bitcoin, non-fungible tokens, and the blockchain is allowing strangers to trust they can exchange value digitally without any intermediaries.

China is currently experimenting with a radical idea known as "a social credit system." It's like a credit score (a previous innovation in trust-building that money lenders use to decipher whether we're trustworthy or not). Instead of just looking at our financial history, the social credit system also looks at additional factors, like whether you have ever been convicted of crimes; whether you donate blood; and whether you park shareable bikes where they're supposed to go. Many Westerners compare the social credit system to George Orwell's 1984 and Black Mirror; it does seem pretty icky. But defenders say it's an innovative way to get more people to trust each other.

Humans, over the long run, may be on a long march to figuring out ways to trust other humans; but the last few decades have shown that march is not inexorably forward. Opinion polls show that trust has been falling in public institutions. Trust in the federal government, for example, has dropped to under 20 percent in recent years, from around 80 percent in the early 1960s. Generalized trust of strangers in your community, aka "social trust," has also been plummeting.

Ho, citing reams of research, offers a few explanations. He blames people's difficulty in trusting strangers who look different from them, which has become a bigger problem as we've seen greater global migration. He also blames rising inequality for the fall of trust: it creates cleavages that make us feel as though we're not living in a harmonious community with leaders who care about us. Finally, Ho blames the Internet, which has created thought bubbles, growing tribalism, and open access to all kinds of trust-destroying disinformation.

But Ho ends his book on a happy note. "The arc of history suggests a positive trend," he writes, in humans developing new ways to overcome their distrust.

It's possible he's too optimistic. But I guess we're just gonna have to trust him on this.

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