How do minds change?

I looked for a scientist who could help me answer a question I had never really considered asking, one that was now making my brain itch. Why do we argue? What purpose does it serve? Is all this bickering online helping or hurting us?

I invited the famed cognitive scientist Hugo Mercier, an expert on human reasoning and argumentation, to be a guest on my show. He explained that we evolved to reach consensus – sometimes on the facts, sometimes on right and wrong, sometimes on what to eat for dinner – by banging our heads together. Groups that did a better job of reaching consensus, by both producing and evaluating arguments, were better at reaching communal goals and out-survived those that didn’t. That led to the innate psychology that compels us to persuade others to see things our way when we believe our groups are misguided.

Mercier told me that if we couldn’t change our minds or the minds of others, there would be no point in arguing in the first place. He asked me to imagine a world where everyone was deaf. “People would stop talking,” he said. The fact that we so often disagree isn’t a bug in human reasoning; it’s a feature. For examples of how arguing had led to sudden shifts, all I had to do was look at the history of change in America.

I found a book about public opinion by political scientist Benjamin Page and Robert Shapiro that revealed since polling began in the early twentieth century, nearly half of the significant opinion shifts in the United States had been, as in the case of same-sec marriage, abrupt. Opinions about abortion, the war in Vietnam, attitudes about race and women and voting rights and smoking and marijuana and many others were stable for years. In each case, arguing had spread from small groups to large, from home to the House of Representatives. Then all at one it seemed that stasis shattered. When the tide of public opinion turned on these issues, it shifted so quickly that if people could step into a time machine and go back just a few years, many would likely argue with themselves with the same fervor they argue about wedge issues today.

I started to see the push and pull of our incessant arguing as a form of punctuated equilibrium. That’s what they call it in biology. When creatures have the capacity to change but there’s little encouragement to do so, they remain mostly the same from one generation to the next. But when the pressure to adapt increases, the pace of evolution increases in response. Over long timescales, a pattern emerges, long stretches of sameness punctuated by periods of rapid change. Looking at the history of social change, revolution, and innovation. It seemed like the same pattern, and I wanted to understand the psychology behind it.

I wondered what was happening inside all those brains before and after they changed their minds. What persuades us, and how? What breaks through resistance so powerfully that we not only see things completely differently, but wonder how we saw it any other way?

How does a person, over the course of a decade, go from being opposed to the “gay agenda” to happily attending a same-sex wedding? How does an entire nation go from smoking on airplanes and offices to banning smoking in bars and restaurants and daytime television? What makes hemlines go up and down and beards appear and disappear? How did marijuana go from a prescription for madness to a prescription for glaucoma? Why don’t you agree with the person who wrote your teenage diary, want or believe the same things, or cut your hair the same way as the person you were just a decade ago? What changed your mind? How do minds change?

From “How Minds Change: The Surprising Science of Belief, Opinion, and Persuasion” by David McRaney