The ideals of the Enlightenment are products of human reason, but they always struggle with other strands of human nature: loyalty to tribe, deference to authority, magical thinking, the blaming of misfortune on evildoers. The second decade of the 21st century has seen the rise of political movements that depict their countries as being pulled into a hellish dystopia by malign factions that can be resisted only by a strong leader who wrenches the country backward to make it “great again.” These movements have been abetted by a narrative shared by many of their fiercest opponents, in which the institutions of modernity have failed and every aspect of life is in deepening crisis—the two sides in macabre agreement that wrecking those institutions will make the world a better place. Harder to find is a positive vision that sees the world’s problems against a background of progress that it seeks to build upon by solving those problems in their turn.
If you still are unsure whether the ideals of Enlightenment humanism need a vigorous defense, consider the diagnosis of Shiraz Maher, an analyst of radical Islamist movements. “The West is shy of its values—it doesn’t speak up for classical liberalism,” he says. “We are unsure of them. They make us feel uneasy.” Contrast that with the Islamic State, which “knows exactly what it stands for,” a certainty that is “incredibly seductive”—and he should know, having once been a regional director of the jihadist group Hizb ut-Tahrir.1
Reflecting on liberal ideals in 1960, not long after they had withstood their greatest trial, the economist Friedrich Hayek observed, “If old truths are to retain their hold on men’s minds, they must be restated in the language and concepts of successive generations” (inadvertently proving his point with the expression men’s minds). “What at one time are their most effective expressions gradually become so worn with use that they cease to carry a definite meaning. The underlying ideas may be as valid as ever, but the words, even when they refer to problems that are still with us, no longer convey the same conviction.”2
This book is my attempt to restate the ideals of the Enlightenment in the language and concepts of the 21st century. I will first lay out a framework for understanding the human condition informed by modern science—who we are, where we came from, what our challenges are, and how we can meet them. The bulk of the book is devoted to defending those ideals in a distinctively 21st-century way: with data. This evidence-based take on the Enlightenment project reveals that it was not a naïve hope. The Enlightenment has worked—perhaps the greatest story seldom told. And because this triumph is so unsung, the underlying ideals of reason, science, and humanism are unappreciated as well. Far from being an insipid consensus, these ideals are treated by today’s intellectuals with indifference, skepticism, and sometimes contempt. When properly appreciated, I will suggest, the ideals of the Enlightenment are in fact stirring, inspiring, noble—a reason to live.
CHAPTER 1
DARE TO UNDERSTAND!
What is enlightenment? In a 1784 essay with that question as its title, Immanuel Kant answered that it consists of “humankind’s emergence from its self-incurred immaturity,” its “lazy and cowardly” submission to the “dogmas and formulas” of religious or political authority.1 Enlightenment’s motto, he proclaimed, is “Dare to understand!” and its foundational demand is freedom of thought and speech. “One age cannot conclude a pact that would prevent succeeding ages from extending their insights, increasing their knowledge, and purging their errors. That would be a crime against human nature, whose proper destiny lies precisely in such progress.”2
A 21st-century statement of the same idea may be found in the physicist David Deutsch’s defense of enlightenment, The Beginning of Infinity. Deutsch argues that if we dare to understand, progress is possible in all fields, scientific, political, and moral:
Optimism (in the sense that I have advocated) is the theory that all failures—all evils—are due to insufficient knowledge. . . . Problems are inevitable, because our knowledge will always be infinitely far from complete. Some problems are hard, but it is a mistake to confuse hard problems with problems unlikely to be solved. Problems are soluble, and each particular evil is a problem that can be solved. An optimistic civilization is open and not afraid to innovate, and is based on traditions of criticism. Its institutions keep improving, and the most important knowledge that they embody is knowledge of how to detect and eliminate errors.3
What is the Enlightenment?4 There is no official answer, because the era named by Kant’s essay was never demarcated by opening and closing ceremonies like the Olympics, nor are its tenets stipulated in an oath or creed. The Enlightenment is conventionally placed in the last two-thirds of the 18th century, though it flowed out of the Scientific Revolution and the Age of Reason in the 17th century and spilled into the heyday of classical liberalism of the first half of the 19th. Provoked by challenges to conventional wisdom from science and exploration, mindful of the bloodshed of recent wars of religion, and abetted by the easy movement of ideas and people, the thinkers of the Enlightenment sought a new understanding of the human condition. The era was a cornucopia of ideas, some of them contradictory, but four themes tie them together: reason, science, humanism, and progress.
Foremost is reason. Reason is nonnegotiable. As soon as you show up to discuss the question of what we should live for (or any other question), as long as you insist that your answers, whatever they are, are reasonable or justified or true and that therefore other people ought to believe them too, then you have committed yourself to reason, and to holding your beliefs accountable to objective standards.5 If there’s anything the Enlightenment thinkers had in common, it was an insistence that we energetically apply the standard of reason to understanding our world, and not fall back on generators of delusion like faith, dogma, revelation, authority, charisma, mysticism, divination, visions, gut feelings, or the hermeneutic parsing of sacred texts.
It was reason that led most of the Enlightenment thinkers to repudiate a belief in an anthropomorphic God who took an interest in human affairs.6 The application of reason revealed that reports of miracles were dubious, that the authors of holy books were all too human, that natural events unfolded with no regard to human welfare, and that different cultures believed in mutually incompatible deities, none of them less likely than the others to be products of the imagination. (As Montesquieu wrote, “If triangles had a god they would give him three sides.”) For all that, not all of the Enlightenment thinkers were atheists. Some were deists (as opposed to theists): they thought that God set the universe in motion and then stepped back, allowing it to unfold according to the laws of nature. Others were pantheists, who used “God” as a synonym for the laws of nature. But few appealed to the law-giving, miracle-conjuring, son-begetting God of scripture.
Many writers today confuse the Enlightenment endorsement of reason with the implausible claim that humans are perfectly rational agents. Nothing could be further from historical reality. Thinkers such as Kant, Baruch Spinoza, Thomas Hobbes, David Hume, and Adam Smith were inquisitive psychologists and all too aware of our irrational passions and foibles. They insisted that it was only by calling out the common sources of folly that we could hope to overcome them. The deliberate application of reason was necessary precisely because our common habits of thought are not particularly reasonable.
That leads to the second ideal, science, the refining of reason to understand the world. The Scientific Revolution was revolutionary in a way that is hard to appreciate today, now that its discoveries have become second nature to most of us. The historian David Wootton reminds us of the understanding of an educated Englishman on the eve of the Revolution in 1600:
He believes witches can summon up storms that sink ships at sea. . . . He believes in werewolves, although there happen not to be any in England—he knows they are to be found in Belgium. . . . He believes Circe really did turn Odysseus’s crew into pigs. He believes mice are spontaneously generated in piles of straw. He believes in contempo
rary magicians. . . . He has seen a unicorn’s horn, but not a unicorn.
He believes that a murdered body will bleed in the presence of the murderer. He believes that there is an ointment which, if rubbed on a dagger which has caused a wound, will cure the wound. He believes that the shape, colour and texture of a plant can be a clue to how it will work as a medicine because God designed nature to be interpreted by mankind. He believes that it is possible to turn base metal into gold, although he doubts that anyone knows how to do it. He believes that nature abhors a vacuum. He believes the rainbow is a sign from God and that comets portend evil. He believes that dreams predict the future, if we know how to interpret them. He believes, of course, that the earth stands still and the sun and stars turn around the earth once every twenty-four hours.7
A century and a third later, an educated descendant of this Englishman would believe none of these things. It was an escape not just from ignorance but from terror. The sociologist Robert Scott notes that in the Middle Ages “the belief that an external force controlled daily life contributed to a kind of collective paranoia”:
Rainstorms, thunder, lightning, wind gusts, solar or lunar eclipses, cold snaps, heat waves, dry spells, and earthquakes alike were considered signs and signals of God’s displeasure. As a result, the “hobgoblins of fear” inhabited every realm of life. The sea became a satanic realm, and forests were populated with beasts of prey, ogres, witches, demons, and very real thieves and cutthroats. . . . After dark, too, the world was filled with omens portending dangers of every sort: comets, meteors, shooting stars, lunar eclipses, the howls of wild animals.8
To the Enlightenment thinkers the escape from ignorance and superstition showed how mistaken our conventional wisdom could be, and how the methods of science—skepticism, fallibilism, open debate, and empirical testing—are a paradigm of how to achieve reliable knowledge.
That knowledge includes an understanding of ourselves. The need for a “science of man” was a theme that tied together Enlightenment thinkers who disagreed about much else, including Montesquieu, Hume, Smith, Kant, Nicolas de Condorcet, Denis Diderot, Jean-Baptiste d’Alembert, Jean-Jacques Rousseau, and Giambattista Vico. Their belief that there was such a thing as universal human nature, and that it could be studied scientifically, made them precocious practitioners of sciences that would be named only centuries later.9 They were cognitive neuroscientists, who tried to explain thought, emotion, and psychopathology in terms of physical mechanisms of the brain. They were evolutionary psychologists, who sought to characterize life in a state of nature and to identify the animal instincts that are “infused into our bosoms.” They were social psychologists, who wrote of the moral sentiments that draw us together, the selfish passions that divide us, and the foibles of shortsightedness that confound our best-laid plans. And they were cultural anthropologists, who mined the accounts of travelers and explorers for data both on human universals and on the diversity of customs and mores across the world’s cultures.
The idea of a universal human nature brings us to a third theme, humanism. The thinkers of the Age of Reason and the Enlightenment saw an urgent need for a secular foundation for morality, because they were haunted by a historical memory of centuries of religious carnage: the Crusades, the Inquisition, witch hunts, the European wars of religion. They laid that foundation in what we now call humanism, which privileges the well-being of individual men, women, and children over the glory of the tribe, race, nation, or religion. It is individuals, not groups, who are sentient—who feel pleasure and pain, fulfillment and anguish. Whether it is framed as the goal of providing the greatest happiness for the greatest number or as a categorical imperative to treat people as ends rather than means, it was the universal capacity of a person to suffer and flourish, they said, that called on our moral concern.
Fortunately, human nature prepares us to answer that call. That is because we are endowed with the sentiment of sympathy, which they also called benevolence, pity, and commiseration. Given that we are equipped with the capacity to sympathize with others, nothing can prevent the circle of sympathy from expanding from the family and tribe to embrace all of humankind, particularly as reason goads us into realizing that there can be nothing uniquely deserving about ourselves or any of the groups to which we belong.10 We are forced into cosmopolitanism: accepting our citizenship in the world.11
A humanistic sensibility impelled the Enlightenment thinkers to condemn not just religious violence but also the secular cruelties of their age, including slavery, despotism, executions for frivolous offenses such as shoplifting and poaching, and sadistic punishments such as flogging, amputation, impalement, disembowelment, breaking on the wheel, and burning at the stake. The Enlightenment is sometimes called the Humanitarian Revolution, because it led to the abolition of barbaric practices that had been commonplace across civilizations for millennia.12
If the abolition of slavery and cruel punishment is not progress, nothing is, which brings us to the fourth Enlightenment ideal. With our understanding of the world advanced by science and our circle of sympathy expanded through reason and cosmopolitanism, humanity could make intellectual and moral progress. It need not resign itself to the miseries and irrationalities of the present, nor try to turn back the clock to a lost golden age.
The Enlightenment belief in progress should not be confused with the 19th-century Romantic belief in mystical forces, laws, dialectics, struggles, unfoldings, destinies, ages of man, and evolutionary forces that propel mankind ever upward toward utopia.13 As Kant’s remark about “increasing knowledge and purging errors” indicates, it was more prosaic, a combination of reason and humanism. If we keep track of how our laws and manners are doing, think up ways to improve them, try them out, and keep the ones that make people better off, we can gradually make the world a better place. Science itself creeps forward through this cycle of theory and experiment, and its ceaseless headway, superimposed on local setbacks and reversals, shows how progress is possible.
The ideal of progress also should not be confused with the 20th-century movement to re-engineer society for the convenience of technocrats and planners, which the political scientist James Scott calls Authoritarian High Modernism.14 The movement denied the existence of human nature, with its messy needs for beauty, nature, tradition, and social intimacy.15 Starting from a “clean tablecloth,” the modernists designed urban renewal projects that replaced vibrant neighborhoods with freeways, high-rises, windswept plazas, and brutalist architecture. “Mankind will be reborn,” they theorized, and “live in an ordered relation to the whole.”16 Though these developments were sometimes linked to the word progress, the usage was ironic: “progress” unguided by humanism is not progress.
Rather than trying to shape human nature, the Enlightenment hope for progress was concentrated on human institutions. Human-made systems like governments, laws, schools, markets, and international bodies are a natural target for the application of reason to human betterment.
In this way of thinking, government is not a divine fiat to reign, a synonym for “society,” or an avatar of the national, religious, or racial soul. It is a human invention, tacitly agreed to in a social contract, designed to enhance the welfare of citizens by coordinating their behavior and discouraging selfish acts that may be tempting to every individual but leave everyone worse off. As the most famous product of the Enlightenment, the Declaration of Independence, put it, in order to secure the right to life, liberty, and the pursuit of happiness, governments are instituted among people, deriving their just powers from the consent of the governed.
Among the powers of government is meting out punishment, and writers such as Montesquieu, Cesare Beccaria, and the American founders thought afresh about the government’s license to harm its citizens.17 Criminal punishment, they argued, is not a mandate to implement cosmic justice but part of an incentive structure that discourages antisocial acts without causing more suffering than it deters. Th
e reason the punishment should fit the crime, for example, is not to balance some mystical scale of justice but to ensure that a wrongdoer stops at a minor crime rather than escalating to a more harmful one. Cruel punishments, whether or not they are in some sense “deserved,” are no more effective at deterring harm than moderate but surer punishments, and they desensitize spectators and brutalize the society that implements them.
The Enlightenment also saw the first rational analysis of prosperity. Its starting point was not how wealth is distributed but the prior question of how wealth comes to exist in the first place.18 Smith, building on French, Dutch, and Scottish influences, noted that an abundance of useful stuff cannot be conjured into existence by a farmer or craftsman working in isolation. It depends on a network of specialists, each of whom learns how to make something as efficiently as possible, and who combine and exchange the fruits of their ingenuity, skill, and labor. In a famous example, Smith calculated that a pin-maker working alone could make at most one pin a day, whereas in a workshop in which “one man draws out the wire, another straights it, a third cuts it, a fourth points it, a fifth grinds it at the top for receiving the head,” each could make almost five thousand.
Specialization works only in a market that allows the specialists to exchange their goods and services, and Smith explained that economic activity was a form of mutually beneficial cooperation (a positive-sum game, in today’s lingo): each gets back something that is more valuable to him than what he gives up. Through voluntary exchange, people benefit others by benefiting themselves; as he wrote, “It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love.” Smith was not saying that people are ruthlessly selfish, or that they ought to be; he was one of history’s keenest commentators on human sympathy. He only said that in a market, whatever tendency people have to care for their families and themselves can work to the good of all.