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

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.