Steven Pinker [heart] the Enlightenment: The Harvard psychologist splits the difference between Dr. Pangloss and Pope Francis.

• Author: Gillespie, Nick
• Position: Interview

STEVEN PINKER IS famous for observing that human material well-being has undergone tremendous, and vastly underrated, improvement over the last few hundred years. "We've got this problem called obesity," the famous Harvard linguist and psychologist wryly notes. "Historically, as problems go, that's a pretty good one to have compared to the alternative of mass starvation."

In 2012's The Better Angels of Our Nature, Pinker argued persuasively that we're "living in the most peaceful moment in our species' existence," with war, crime, and abject poverty all at historic lows. Microsoft founder Bill Gates called it "the most inspiring book I've ever read."

Many people assume this all means Pinker sees advancements as inevitable, irreversible. Not so, he insists: "We're always in danger of losing them," particularly if we forget the principles and commitments that have made possible the miracle of modern life.

In his telling, the world as we know it grew out of the Enlightenment, a philosophical movement that dominated Europe's culture in the 18th century and directly informed the great American idea that all people have inalienable rights to life, liberty, and the pursuit of happiness. But these all-important values are fragile, he explains in a new book, Enlightenment Now: The Case for Reason, Science, Humanism, and Progress (Viking), and the presumption in their favor is fraying under pressure from both left and right.

Pinker has been named among the 100 most influential public intellectuals by both Time magazine and Foreign Policy, though he may be even better known as the first nominee to the Luxuriant Flowing Hair Club for Scientists, a project of the satirical Annals of Improbable Research. In March, he visited Reason's Washington, D.C., office to talk with Nick Gillespie about his work.

Reason: What comprises the Enlightenment?

Steven Pinker: My point of view identifies four things: reason, science, humanism, and progress. Reason being the ideal that we analyze our predicament using reason as opposed to dogma, authority, charisma, intuition, mysticism. Science being the ideal that we seek to understand the world by formulating hypotheses and testing them against reality. Humanism, that we hold out the well-being of men, women, children, and other sentient creatures as the highest good, as opposed to the glory of the tribe or the race or the nation, and as opposed to religious doctrine. And progress, that if we apply sympathy and reason to making people better off, we can gradually succeed.

Why did the Enlightenment happen when it did?

Because it only happened once, we don't really know and we can't test hypotheses. But some plausible explanations are that it grew out of the scientific revolution of the 17th century, which showed that our intuitions and the traditional view of reality could be profoundly mistaken, and that by applying reason, we can overturn our understanding of the world.

Maybe the more proximate technological kickstarter was the growth of printing technology. That was the only technology that showed a huge increase in productivity prior to the Industrial Revolution. Everything else had to wait for the 19th century.

Between the year 1000 and about 1800, people in many places saw very little increase in material well-being.

Yeah. Economic growth was sporadic at best. But printing technology did take off in the 18th century. Pamphlets were cheap and available, and broadsheets and books, and they got translated. They were circulated across all of the European countries as well as the colonies, so that the exchange of ideas was lubricated by that technological advance.

Another possible contributor was the historic memory of the wars of religion. That showed that dogmas about faith and scripture and interpretation and messiahs and so on could lead to tremendous carnage, and people thought, "Let's not do that again." These are all the ingredients. Which one was causal, we don't know.

A large section of the book documents the incredible material progress that we've made. What for you are some of the key markers that show the impact of Enlightenment thinking on our world?

Certainly the conquest of hunger--the fact that now we've got this problem called obesity, the obesity epidemic. Historically, as problems go, that's a pretty good one to have compared to the alternative of mass starvation.

There still is hunger, especially in war-torn, remote regions, but by and large famine--one of the Horsemen of the Apocalypse--has been tamed. And sheer longevity, the fact that in the world as a whole, life expectancy now is 71. For most of human history, it was 30. Literacy--the fact that 90 percent of people under the age of 25 can read and write, when in Europe a couple of hundred years ago it was 15 percent. Less obviously, war has been in decline over the past 70 years or so, and crime has declined, even in a pretty crime-prone country like the United States.

But violent crime on a day-to-day basis started declining in the late Middle Ages, right?

Yeah, so we can't credit the Enlightenment for that, because it was part of the transition to modernity. But it got a boost in the 19th century with the formation of professional police forces and with the more systematic application of criminal justice, and then another boost in the 1990s and the 21st century with data-driven policing.

I found one insight related to criminal justice really interesting. Talk about the idea of having a prison sentence or a sanction against a criminal fit the crime.

Prior to the Enlightenment, there were gruesome criminal punishments for what we would consider rather trivial misdemeanors. Drawing and quartering, cutting a person open, ripping out his entrails while he was still alive and conscious.

I'm sure he was guilty of something, right?

Poaching. Criticizing the royal garden. Then in the 18th century, Cesare Beccaria, who also coined the term "the greatest good for the greatest number"--later picked up by Jeremy Bentham as a model for utilitarianism--argued for proportionality. Not so much to satisfy some cosmic scale of justice, but just to set up the right incentive structure. He pointed out that if you're going to apply the severest penalty to rather minor crimes, criminals could say, "Well, why stop at that? If I'm going to take a chance, I may as well go all the way--kill the witnesses, kill the witnesses' families, if I'm going to get the same punishment as just burglarizing the house in the first place." It's a real rational, incentive-based argument.

You say, "The world has made spectacular progress in every single measure of human well-being. Here is a second shocker. Almost no one knows about it." Why don't we acknowledge that more?

...