Enlightenment Now: The Case for Reason, Science, Humanism, and Progress

Reasoning thus has deep evolutionary roots. The citizen scientist Louis Liebenberg has studied the San hunter-gatherers of the Kalahari Desert (the “Bushmen”), one of the world’s most ancient cultures. They engage in the oldest form of the chase, persistence hunting, in which humans, with their unique ability to dump heat through sweat-slicked skin, pursue a furry mammal in the midday sun until it collapses of heat stroke. Since most mammals are swifter than humans and dart out of sight as soon as they are spotted, persistence hunters track them by their spoor, which means inferring the animal’s species, sex, age, and level of fatigue, and thus its likely direction of flight, from the hoofprints, bent stems, and displaced pebbles it leaves behind. The San do not just engage in inference—deducing, for example, that agile springboks tread deeply with pointed hooves to get a good grip, whereas heavy kudus tread flat-footed to support their weight. They also engage in reasoning—articulating the logic behind their inferences to persuade their companions or be persuaded in their turn. Liebenberg observed that Kalahari trackers don’t accept arguments from authority. A young tracker can challenge the majority opinion of his elders, and if his interpretation of the evidence is convincing, he can bring them around, increasing the group’s accuracy.⁸

And if you’re still tempted to excuse modern dogma and superstition by saying that it’s only human, consider Liebenberg’s account of scientific skepticism among the San:

Three trackers, !Nate, /Uase and Boroh//xao, of Lone Tree in the central Kalahari, told me that the Monotonous Lark (Mirafra passerina) only sings after it has rained, because “it is happy that it rained.” One tracker, Boroh//xao, told me that when the bird sings, it dries out the soil, making the roots good to eat. Afterwards, !Nate and /Uase told me that Boroh//xao was wrong—it is not the bird that dries out the soil, it is the sun that dries out the soil. The bird is only telling them that the soil will dry out in the coming months and that it is the time of the year when the roots are good to eat. . . .

!Namka, a tracker from Bere in the central Kalahari, Botswana, told me the myth of how the sun is like an eland, which crosses the sky and is then killed by people who live in the west. The red glow in the sky when the sun goes down is the blood of the eland. After they have eaten it, they throw the shoulder blade across the sky back to the east, where it falls into a pool and grows into a new sun. Sometimes, it is said, you can hear the swishing noise of the shoulder blade flying through the air. After telling me the story in great detail, he told me that he thinks that the “Old People” lied, because he has never seen . . . the shoulder blade fly through the sky or heard the swishing noise.⁹

Of course, none of this contradicts the discovery that humans are vulnerable to illusions and fallacies. Our brains are limited in their capacity to process information and evolved in a world without science, scholarship, and other forms of fact-checking. But reality is a mighty selection pressure, so a species that lives by ideas must have evolved with an ability to prefer correct ones. The challenge for us today is to design an informational environment in which that ability prevails over the ones that lead us into folly. The first step is to pinpoint why an otherwise intelligent species is so easily led into folly.

The 21st century, an age of unprecedented access to knowledge, has also seen maelstroms of irrationality, including the denial of evolution, vaccine safety, and anthropogenic climate change, and the promulgation of conspiracy theories, from 9/11 to the size of Donald Trump’s popular vote. Fans of rationality are desperate to understand the paradox, but in a bit of irrationality of their own, they seldom look at data that might explain it.

The standard explanation of the madness of crowds is ignorance: a mediocre education system has left the populace scientifically illiterate, at the mercy of their cognitive biases, and thus defenseless against airhead celebrities, cable-news gladiators, and other corruptions from popular culture. The standard solution is better schooling and more outreach to the public by scientists on television, social media, and popular Web sites. As an outreaching scientist I’ve always found this theory appealing, but I’ve come to realize it’s wrong, or at best a small part of the problem.

Consider these questions about evolution:

During the Industrial Revolution of the 19th century, the English countryside got covered in soot, and the Peppered Moth became, on average, darker in color. How did this happen?

A. In order to blend in with their surroundings, the moths had to become darker in color.

B. The moths with darker color were less likely to get eaten and were more likely to reproduce.