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

by Steven Pinker

Unfortunately, the expressive rationality documented by Kahan in his experimental subjects also applies to editorialists and experts. The payoffs that determine their reputations don’t coincide with the accuracy of the predictions, since no one is keeping score. Instead, their reputations hinge on their ability to entertain, titillate, or shock; on their ability to instill confidence or fear (in the hopes that a prophecy might be self-fulfilling or self-defeating); and on their skill in galvanizing a coalition and celebrating its virtue.

To my mind, Tetlock’s hardheaded appraisal of expertise by the ultimate benchmark, prediction, should revolutionize our understanding of history, politics, epistemology, and intellectual life. What does it mean that the wonkish tweaking of probabilities is a more reliable guide to the world than the pronouncements of erudite sages and narratives inspired by systems of ideas? Aside from smacking us upside the head with a reminder to be more humble and open-minded, it offers a glimpse into the workings of history on the time scale of years and decades. Events are determined by myriad small forces incrementing or decrementing their likelihoods and magnitudes rather than by sweeping laws and grand dialectics. Unfortunately for many intellectuals and for all political ideologues, this is not the way they are accustomed to thinking, but perhaps we had better get used to it. When Tetlock was asked at a public lecture to forecast the nature of forecasting, he said, “When the audience of 2515 looks back on the audience of 2015, their level of contempt for how we go about judging political debate will be roughly comparable to the level of contempt we have for the 1692 Salem witch trials.”

The major enemy of reason in the public sphere today—which is not ignorance, innumeracy, or cognitive biases, but politicization—appears to be on an upswing. In the political arena itself, Americans have become increasingly polarized.50 Most people’s opinions are too shallow and uninformed to fit into a coherent ideology, but in a dubious form of progress, the percentage of Americans whose opinions are down-the-line liberal or down-the-line conservative doubled between 1994 and 2014, from 10 to 21 percent. The polarization has coincided with an increase in social segregation by politics: over those twenty years, the ideologues have become more likely to say that most of their close friends share their political views. The parties have become more partisan as well. According to a recent Pew study, in 1994 about a third of Democrats were more conservative than the median Republican, and vice-versa. In 2014 the figures were closer to a twentieth. Though Americans across the political spectrum drifted leftward through 2004, since then they have diverged on every major issue except gay rights, including government regulation, social spending, immigration, environmental protection, and military strength. Even more troublingly, each side has become more contemptuous of the other. In 2014, 38 percent of Democrats held “very unfavorable” views of the Republican Party (up from 16 percent in 1994), and more than a quarter saw it as “a threat to the nation’s well-being.” Republicans w...

Of the two forms of politicization that are subverting reason today, the political is far more dangerous than the academic, for an obvious reason. It’s often quipped (no one knows who said it first) that academic debates are vicious because the stakes are so small.70 But in political debates the stakes are unlimited, including the future of the planet. Politicians, unlike professors, pull the levers of power. In 21st-century America, the control of Congress by a Republican Party that became synonymous with the extreme right has been pernicious, because it is so convinced of the righteousness of its cause and the evil of its rivals that it has undermined the institutions of democracy to get what it wants. The corruptions include gerrymandering, imposing voting restrictions designed to disenfranchise Democratic voters, encouraging unregulated donations from moneyed interests, blocking Supreme Court nominations until their party controls the presidency, shutting down the government when their maximal demands aren’t met, and unconditionally supporting Donald Trump over their own objections to his flagrantly antidemocratic impulses.71 Whatever differences in policy or philosophy divide the parties, the mechanisms of democratic deliberation should be sacrosanct. Their erosion, disproportionately by the right, has led many people, including a growing share of young Americans, to see democratic government as inherently dysfunctional and to become cynical about democracy itself.

Making reason the currency of our discourse begins with clarity about the centrality of reason itself.74 As I mentioned, many commentators are confused about it. The discovery of cognitive and emotional biases does not mean that “humans are irrational” and so there’s no point in trying to make our deliberations more rational. If humans were incapable of rationality, we could never have discovered the ways in which they were irrational, because we would have no benchmark of rationality against which to assess human judgment, and no way to carry out the assessment. Humans may be vulnerable to bias and error, but clearly not all of us all the time, or no one would ever be entitled to say that humans are vulnerable to bias and error. The human brain is capable of reason, given the right circumstances; the problem is to identify those circumstances and put them more firmly in place.

Indeed, in one realm after another we are seeing the conquest of dogma and instinct by the armies of reason. Newspapers are supplementing shoe leather and punditry with statisticians and fact-checking squads.93 The cloak-and-dagger world of national intelligence is seeing farther into the future by using the Bayesian reasoning of superforecasters.94 Health care is being reshaped by evidence-based medicine (which should have been a redundant expression long ago).95 Psychotherapy has progressed from the couch and notebook to Feedback-Informed Treatment.96 In New York, and increasingly in other cities, violent crime has been reduced with the real-time data-crunching system called Compstat.97 The effort to aid the developing world is being guided by the Randomistas, economists who gather data from randomized trials to distinguish fashionable boondoggles from programs that actually improve people’s lives.98 Volunteering and charitable giving are being scrutinized by the Effective Altruism movement, which distinguishes altruistic acts that enhance the lives of beneficiaries from those that enhance the warm glow in benefactors.99 Sports has seen the advent of Moneyball, in which strategies and players are evaluated by statistical analysis rather than intuition and lore, allowing smarter teams to beat richer teams and giving fans endless new material for conversations over the hot stove.100 The blogosphere has spawned the Rationality Community, who urge people to be “less wrong” i...

An endorsement of scientific thinking must first of all be distinguished from any belief that members of the occupational guild called “science” are particularly wise or noble. The culture of science is based on the opposite belief. Its signature practices, including open debate, peer review, and double-blind methods, are designed to circumvent the sins to which scientists, being human, are vulnerable. As Richard Feynman put it, the first principle of science is “that you must not fool yourself—and you are the easiest person to fool.” For the same reason, a call for everyone to think more scientifically must not be confused with a call to hand decision-making over to scientists. Many scientists are naïfs when it comes to policy and law, and cook up nonstarters like world government, mandatory licensing of parents, and escaping a befouled Earth by colonizing other planets. It doesn’t matter, because we’re not talking about which priesthood should be granted power; we’re talking about how collective decisions can be made more wisely.

All the methods are pressed into the service of two ideals, and it is these ideals that advocates of science want to export to the rest of intellectual life. The first is that the world is intelligible. The phenomena we experience may be explained by principles that are deeper than the phenomena themselves. That’s why scientists laugh at the Theory of the Brontosaurus from the dinosaur expert on Monty Python’s Flying Circus: “All brontosauruses are thin at one end, much much thicker in the middle, and then thin again at the far end”—the “theory” is just a description of how things are, not an explanation of why they are the way they are. The principles making up an explanation may in turn be explained by still deeper principles, and so on. (As David Deutsch put it, “We are always at the beginning of infinity.”) In making sense of our world, there should be few occasions on which we are forced to concede, “It just is” or “It’s magic” or “Because I said so.” The commitment to intelligibility is not a matter of raw faith, but progressively validates itself as more of the world becomes explicable in scientific terms. The processes of life, for example, used to be attributed to a mysterious élan vital; now we know they are powered by chemical and physical reactions among complex molecules.

The second ideal is that we must allow the world to tell us whether our ideas about it are correct. The traditional causes of belief—faith, revelation, dogma, authority, charisma, conventional wisdom, hermeneutic parsing of texts, the glow of subjective certainty—are generators of error, and should be dismissed as sources of knowledge. Instead our beliefs about empirical propositions should be calibrated by their fit to the world. When scientists are pressed to explain how they do this, they usually reach for Karl Popper’s model of conjecture and refutation, in which a scientific theory may be falsified by empirical tests but is never confirmed. In reality, science doesn’t much look like skeet shooting, with a succession of hypotheses launched into the air like clay pigeons and shot to smithereens. It looks more like Bayesian reasoning (the logic used by the superforecasters we met in the preceding chapter). A theory is granted a prior degree of credence, based on its consistency with everything else we know. That level of credence is then incremented or decremented according to how likely an empirical observation would be if the theory is true, compared with how likely it would be if the theory is false.19 Regardless of whether Popper or Bayes has the better account, a scientist’s degree of belief in a theory depends on its consistency with empirical evidence. Any movement that calls itself “scientific” but fails to nurture opportunities for the testing of its own beliefs...

Does the demonization of science in the liberal arts programs of higher education matter? It does, for a number of reasons. Though many talented students hurtle along pre-med or engineering tracks from the day they set foot on campus, many others are unsure of what they want to do with their lives and take their cues from their professors and advisors. What happens to those who are taught that science is just another narrative like religion and myth, that it lurches from revolution to revolution without making progress, and that it is a rationalization of racism, sexism, and genocide? I’ve seen the answer: some of them figure, “If that’s what science is, I might as well make money!” Four years later their brainpower is applied to thinking up algorithms that allow hedge funds to act on financial information a few milliseconds faster rather than to finding new treatments for Alzheimer’s disease or technologies for carbon capture and storage.

In 1778 Thomas Paine extolled the cosmopolitan virtues of science: Science, the partisan of no country, but the beneficent patroness of all, has liberally opened a temple where all may meet. Her influence on the mind, like the sun on the chilled earth, has long been preparing it for higher cultivation and further improvement. The philosopher of one country sees not an enemy in the philosophy of another: he takes his seat in the temple of science, and asks not who sits beside him.63 What he wrote about the physical landscape applies as well to the landscape of knowledge. In this and other ways, the spirit of science is the spirit of the Enlightenment.

The goal of maximizing human flourishing—life, health, happiness, freedom, knowledge, love, richness of experience—may be called humanism. (Despite the word’s root, humanism doesn’t exclude the flourishing of animals, but this book focuses on the welfare of humankind.) It is humanism that identifies what we should try to achieve with our knowledge. It provides the ought that supplements the is. It distinguishes true progress from mere mastery.

Though humanism does not invoke gods, spirits, or souls to ground meaning and morality, it is by no means incompatible with religious institutions. Some Eastern religions, including Confucianism and varieties of Buddhism, always grounded their ethics in human welfare rather than divine dictates. Many Jewish and Christian denominations have become humanistic, soft-pedaling their legacy of supernatural beliefs and ecclesiastical authority in favor of reason and universal human flourishing.

Humanism may seem bland and unexceptionable—who could be against human flourishing? But in fact it is a distinctive moral commitment, one that does not come naturally to the human mind. As we shall see, it is vehemently opposed not just by many religious and political factions but, amazingly, by eminent artists, academics, and intellectuals. If humanism, like the other Enlightenment ideals, is to retain its hold on people’s minds, it must be explained and defended in the language and ideas of the current era.

Spinoza’s dictum is one of a family of principles that have sought a secular foundation for morality in impartiality—in the realization that there’s nothing magic about the pronouns I and me that could justify privileging my interests over yours or anyone else’s.

The physical requirements that allow rational agents to exist in the material world are not abstract design specifications; they are implemented in the brain as wants, needs, emotions, pains, and pleasures. On average, and in the kind of environment in which our species was shaped, pleasurable experiences allowed our ancestors to survive and have viable children, and painful ones led to a dead end. That means that food, comfort, curiosity, beauty, stimulation, love, sex, and camaraderie are not shallow indulgences or hedonistic distractions. They are links in the causal chain that allowed minds to come into being. Unlike ascetic and puritanical regimes, humanistic ethics does not second-guess the intrinsic worth of people seeking comfort, pleasure, and fulfillment—if people didn’t seek them, there would be no people. At the same time, evolution guarantees that these desires will work at cross-purposes with each other and with those of other people.9 Much of what we call wisdom consists in balancing the conflicting desires within ourselves, and much of what we call morality and politics consists in balancing the conflicting desires among people.

Even when humanistic movements fortify their goals with the language of rights, the philosophical system justifying those rights must be “thin.”21 A viable moral philosophy for a cosmopolitan world cannot be constructed from layers of intricate argumentation or rest on deep metaphysical or religious convictions. It must draw on simple, transparent principles that everyone can understand and agree upon. The ideal of human flourishing—that it’s good for people to lead long, healthy, happy, rich, and stimulating lives—is just such a principle, since it is based on nothing more (and nothing less) than our common humanity.

The Universal Declaration of Human Rights, a humanist manifesto with thirty articles, was drafted in less than two years, thanks to the determination of Eleanor Roosevelt, chair of the drafting committee, to avoid getting mired in ideology and move the project along.24 (When John Humphrey, author of the first draft, was asked on what principles the Declaration was based, he tactfully replied, “No philosophy whatsoever.”)25 In December 1948 it was passed without opposition by the UN General Assembly. Contrary to accusations that human rights are a parochial Western creed, the Declaration was supported by India, China, Thailand, Burma, Ethiopia, and seven Muslim countries, while Roosevelt had to twist the arms of American and British officials to get them behind it: the United States was worried about its Negroes, the United Kingdom about its colonies. The Soviet bloc, Saudi Arabia, and South Africa abstained.

Though humanism is the moral code that people will converge upon when they are rational, culturally diverse, and need to get along, it is by no means a vapid or saccharine lowest common denominator. The idea that morality consists in the maximization of human flourishing clashes with two perennially seductive alternatives. The first is theistic morality: the idea that morality consists in obeying the dictates of a deity, which are enforced by supernatural reward and punishment in this world or in an afterlife. The second is romantic heroism: the idea that morality consists in the purity, authenticity, and greatness of an individual or a nation. Though romantic heroism was first articulated in the 19th century, it may be found in a family of newly influential movements, including authoritarian populism, neo-fascism, neo-reaction, and the alt-right.

Other components of theistic morality, such as the existence of an immaterial soul and a realm of reality beyond matter and energy, are just as testable. We might discover a severed head that can speak. A seer could predict the exact day of natural disasters and terrorist attacks. Aunt Hilda could beam a message from the Great Beyond telling us under which floorboard she hid her jewelry. Memoirs from oxygen-starved patients who experienced their souls leaving their bodies could contain verifiable details unavailable to their sense organs. The fact that these reports have all been exposed as tall tales, false memories, overinterpreted coincidences, and cheap carny tricks undermines the hypothesis that there are immaterial souls which could be subject to divine justice.34 There are, of course, deistic philosophies in which God created the universe and then stepped back to watch what happened, or in which “God” is merely a synonym for the laws of physics and mathematics. But these impotent Gods are in no position to underwrite morality.

Anyone who wants to go beyond personality in understanding authoritarian populism must appreciate the two ideologies behind them, both of them militantly opposed to Enlightenment humanism and each influenced, in different ways, by Nietzsche. One is fascist, the other reactionary—not in the common left-wing sense of “anyone who is more conservative than me,” but in their original, technical senses.

the movements are similar in their reactionary mindset, with its horror of modernity and progress.124 Both believe that at some time in the past there was a happy, well-ordered state where a virtuous people knew their place. Then alien secular forces subverted this harmony and brought on decadence and degeneration. Only a heroic vanguard with memories of the old ways can restore the society to its golden age.

With the stakes this high, it’s good to remind ourselves why the case for neo-theo-reactionary-populist nationalism is intellectually bankrupt. I have already discussed the absurdity of seeking a foundation for morality in the institutions that brought us the Crusades, the Inquisition, the witch hunts, and the European wars of religion. The idea that the global order should consist of ethnically homogeneous and mutually antagonistic nation-states is just as ludicrous.

In reality, the cognitive category of a tribe, in-group, or coalition is abstract and multidimensional.126 People see themselves as belonging to many overlapping tribes: their clan, hometown, native country, adopted country, religion, ethnic group, alma mater, fraternity or sorority, political party, employer, service organization, sports team, even brand of camera equipment.

The claim that ethnic uniformity leads to cultural excellence is as wrong as an idea can be. There’s a reason we refer to unsophisticated things as provincial, parochial, and insular and to sophisticated ones as urbane and cosmopolitan. No one is brilliant enough to dream up anything of value all by himself. Individuals and cultures of genius are aggregators, appropriators, greatest-hit collectors. Vibrant cultures sit in vast catchment areas in which people and innovations flow from far and wide.

Remember your math: an anecdote is not a trend. Remember your history: the fact that something is bad today doesn’t mean it was better in the past. Remember your philosophy: one cannot reason that there’s no such thing as reason, or that something is true or good because God said it is. And remember your psychology: much of what we know isn’t so, especially when our comrades know it too. Keep some perspective. Not every problem is a Crisis, Plague, Epidemic, or Existential Threat, and not every change is the End of This, the Death of That, or the Dawn of a Post-Something Era. Don’t confuse pessimism with profundity: problems are inevitable, but problems are solvable, and diagnosing every setback as a symptom of a sick society is a cheap grab for gravitas. Finally, drop the Nietzsche. His ideas may seem edgy, authentic, baaad, while humanism seems sappy, unhip, uncool. But what’s so funny about peace, love, and understanding? The case for Enlightenment Now is not just a matter of debunking fallacies or disseminating data. It may be cast as a stirring narrative, and I hope that people with more artistic flair and rhetorical power than I can tell it better and spread it farther. The story of human progress is truly heroic. It is glorious. It is uplifting. It is even, I daresay, spiritual. It goes something like this. We are born into a pitiless universe, facing steep odds against life-enabling order and in constant jeopardy of falling apart. We were shaped by a force that is ...