Harish and Debra are facing off in San Francisco in February 2019 in front of a large crowd. They’ve been kept in the dark about the debate topic. When they walk onstage, the moderator announces the subject: should preschools be subsidized by the government?

After just fifteen minutes of preparation, Debra will present her strongest arguments in favor of subsidies, and Harish will marshal his best case against them. Their goal is to win the audience over to their side on preschool subsidies, but their impact on me will be much broader: they’ll end up changing my view of what it takes to win a debate.

Debra kicks off with a joke, drawing laughter from the crowd by telling Harish that although he may hold the world record in debate wins, he’s never debated someone like her. Then she goes on to summarize an impressive number of studies—citing her sources—about the academic, social, and professional benefits of preschool programs. For good measure, she quotes a former prime minister’s argument about preschool being a smart investment.

Harish acknowledges the facts that Debra presented, but then makes his case that subsidizing preschools is not the appropriate remedy for the damage caused by poverty. He suggests that the issue should be evaluated on two grounds: whether preschool is currently underprovided and underconsumed, and whether it helps those who are the least fortunate. He argues that in a world full of trade-offs, subsidizing preschool is not the best use of taxpayer money.

Going into the debate, 92 percent of the audience has already made up their minds. I’m one of them: it didn’t take me long to figure out where I stood on preschool subsidies. In the United States, public education is free from kindergarten through high school. I’m familiar with evidence that early access to education in the first few years of children’s lives may be even more critical to helping them escape poverty than anything they learn later. I believe education is a fundamental human right, like access to water, food, shelter, and health care. That puts me on Team Debra. As I watch the debate, her early arguments strike a chord. Here are some highlights:

Debra: Research clearly shows that a good preschool can help kids overcome the disadvantages often associated with poverty.

Data for the win! Be still, my beating heart.

Debra: You will possibly hear my opponent talk today about different priorities . . . he might say that subsidies are needed, but not for preschools. I would like to ask you, Mr. Natarajan . . . why don’t we examine the evidence and the data and decide accordingly?

If Harish has an Achilles’ heel, my former student has told me, it’s that his brilliant arguments aren’t always grounded in facts.

Harish: Let me start by examining the main claim . . . that if we believe preschools are good in principle, surely it is worth giving money to subsidize those—but I don’t think that is ever enough of a justification for subsidies.

Debra has clearly done her homework. She didn’t just nail Harish on data—she anticipated his counterargument.

Debra: The state budget is a big one, and there is room in it to subsidize preschools and invest in other fields. Therefore, the idea that there are more important things to spend on is irrelevant, because the different subsidies are not mutually exclusive.

Way to debunk Harish’s case for trade-offs. Bravo.

Harish: Maybe the state has the budget to do all the good things. Maybe the state has the budget to provide health care. Maybe it has the budget to provide welfare payments. Maybe it has the budget to provide running water as well as preschool. I would love to live in that world, but I don’t think that is the world we live in. I think we live in a world where there are real constraints on what governments can spend money on—and even if those are not real, those are nonetheless political.

D’oh! Valid point. Even if a program has the potential to pay for itself, it takes a lot of political capital to make it happen—capital that could be invested elsewhere.

Debra: Giving opportunities to the less fortunate should be a moral obligation of any human being, and it is a key role for the state. To be clear, we should find the funding for preschools and not rely on luck or market forces. This issue is too important to not have a safety net.

Yes! This is more than a political or an economic question. It’s a moral question.

Harish: I want to start by noting what [we] agree on. We agree that poverty is terrible. It is terrible when individuals do not have running water. It is terrible when . . . they are struggling to feed their family. It is terrible when they cannot get health care. . . . That is all terrible, and those are all things we need to address, and none of those are addressed just because you are going to subsidize preschool. Why is that the case?

Hmm. Can Debra argue otherwise?

Debra: Universal full-day preschool creates significant economic savings in health care as well as decreased crime, welfare dependence, and child abuse.

Harish: High-quality preschools will reduce crime. Maybe, but so would other measures in terms of crime prevention.

Debra: High-quality preschool boosts high school graduation rates.

Harish: High-quality preschools can lead to huge improvements in individuals’ lives. Maybe, but I’m not sure if you massively increase the number of people going to preschool, they’re all gonna be the ones going to the high-quality preschools.

Uh-oh. Harish is right: there’s a risk that children from the poorest families will end up in the worst preschools. I’m starting to rethink my position.

Harish: Even when you subsidize preschools, it doesn’t mean that all individuals go. . . . The question is, who do you help? And the people you don’t help are those individuals who are the poorest. You give unfair and exaggerated gains to those individuals who are in the middle class.

Point taken. Since preschool won’t be free, the underprivileged still might not be able to afford it. Now I’m torn about where I stand.

You’ve seen arguments from both sides. Before I tell you who won, consider your own position: what was your opinion of preschool subsidies going into the debate, and how many times did you end up rethinking that opinion?

If you’re like me, you reconsidered your views multiple times. Changing your mind doesn’t make you a flip-flopper or a hypocrite. It means you were open to learning.

Looking back, I’m disappointed in myself for forming an opinion before the debate even started. Sure, I’d read some research on early child development, but I was clueless about the economics of subsidies and the alternative ways those funds could be invested. Note to self: on my next trip to the top of Mount Stupid, remember to take a selfie.

In the audience poll after the debate, the number of undecided people was the same, but the balance of opinion shifted away from Debra’s position, toward Harish’s. Support for preschool subsidies dropped from 79 to 62 percent, and opposition more than doubled from 13 to 30 percent. Debra not only had more data, better evidence, and more evocative imagery—she had the audience on her side going into the debate. Yet Harish convinced a number of us to rethink our positions. How did he do it, and what can we learn from him about the art of debate?

This section of the book is about convincing other people to rethink their opinions. When we’re trying to persuade people, we frequently take an adversarial approach. Instead of opening their minds, we effectively shut them down or rile them up. They play defense by putting up a shield, play offense by preaching their perspectives and prosecuting ours, or play politics by telling us what we want to hear without changing what they actually think. I want to explore a more collaborative approach—one in which we show more humility and curiosity, and invite others to think more like scientists.

THE SCIENCE OF THE DEAL

A few years ago a former student named Jamie called me for advice on where to go to business school. Since she was already well on her way to building a successful career, I told her it was a waste of time and money. I walked her through the lack of evidence that a graduate degree would make a tangible difference in her future, and the risk that she’d end up overqualified and underexperienced. When she insisted that her employer expected an MBA for promotions, I told her that I knew of exceptions and pointed out that she probably wouldn’t spend her whole career at that firm anyway. Finally, she hit back: “You’re a logic bully!”

A what?

“A logic bully,” Jamie repeated. “You just overwhelmed me with rational arguments, and I don’t agree with them, but I can’t fight back.”

At first I was delighted by the label. It felt like a solid description of one of my roles as a social scientist: to win debates with the best data. Then Jamie explained that my approach wasn’t actually helpful. The more forcefully I argued, the more she dug in her heels. Suddenly I realized I had instigated that same kind of resistance many times before.

     David Sipress/The New Yorker Collection/The Cartoon Bank; ? Condé Nast