At the moment of writing, liberal ideas are under threat,” declares Oxford’s Ritchie Robertson in The Enlightenment: The Pursuit of Happiness, 1680–1790. The Enlightenment has recently become a touchstone for culture-war debates about tolerance and open-mindedness, and Robertson has written a rich new study of a fascinating period. Critics of the era typically pick and choose among many strands of Enlightenment thinking to create a hybrid “Enlightenment project” composed of everything they dislike. “[T]he Enlightenment project,” writes Robertson, “is a phrase beloved of philosophers but regarded skeptically by historians…. In lambasting the Enlightenment, its critics are seizing on a scapegoat which is much easier to name than the vast, inchoate tangle of forces that are actually responsible” for current social and political ills. The time is ripe for what he calls a “fine-grained presentation” of the period to clear up misconceptions and provide historical nuance.

A professor of German language and literature, Robertson knows that writing good history means clearing away easy preconceptions. His work implies that to understand the Enlightenment, or perhaps any period, it is less useful to distill a set of theses than to identify a group of questions that people agreed were important, even if they furnished very different answers. Thus he avoids sweeping generalizations and focuses on the particular: he has an eye for revealing anecdotes and memorable quotations. Even unfounded rumors—if they were circulated widely enough at the time—can help reveal an age’s concerns. Robertson recounts the story that Julien Offray de La Mettrie, a French materialist philosopher who advocated indulging sensual urges, died “by keeling over at a Berlin dinner-table after gorging on truffles.” It was also widely believed that a Viennese catalog of books forbidden by the Catholic Church “was itself placed on the catalog of prohibited books,” so people could not learn what they were not allowed to read! These telling points of detail help convey the atmosphere of Europe during the 18th century, when spiritual, intellectual, and cultural orthodoxy was giving way to the daring new ideas expressed and lived out among social elites.

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For Robertson, Enlightenment thinkers believed above all in “the pursuit of happiness” (usually left undefined) rather than of salvation. He emphasizes the achievements of what he calls “the practical Enlightenment”: all those improvements in technology, medicine, and policy designed to better people’s lives in this world rather than secure their fate in the next. It was an age of tinkering, when Lockean empiricism gradually replaced Cartesian rationalism. Provisional improvements, rather than timeless truths, became the order of the day. Some looked to enlightened monarchs to enact reforms, as Voltaire and other “mainstream” philosophers did. Others, like Thomas Paine and Maximilien Robespierre, placed their hopes in radical republicanism. But almost all demonstrated a concern with the governing questions of how society might be improved and happiness achieved.

Thus, another major question at issue was: what holds society together? Some, like Thomas Hobbes, insisted that self-interest motivates people to build civilizations for the sake of their own personal safety. This line of thinking—still prevalent in many economics departments—reduces all apparent altruism to disguised selfishness. Other thinkers, such as Anthony Ashley-Cooper, Earl of Shaftesbury, insisted that we are by nature sympathetic to others. The Scottish economist Adam Smith—today mistakenly associated with the school of pure selfishness—argued in his Theory of Moral Sentiments (1759) that concern for others is “an original passion,” meaning that it does not secretly boil down to self-interest or anything else.

With observations like these, Robertson clears away a popular but mistaken caricature of the Enlightenment as a time when people valued nothing except cold, abstract reason. To the contrary, “[r]eason is and ought only to be the slave of the passions,” David Hume declared in his Treatise of Human Nature (1739-40). Many Enlightenment thinkers considered it essential to develop “sensibility,” or sensitivity to human feeling, through art and literature. In Robertson’s view, historians often overlook this fact because they discount novels as derivative, sugar-coated presentations of ideas pioneered among philosophers. But as the literary scholar Mikhail Bakhtin observed, the importance of sensibility is one of many ideas that were first extensively developed in fiction. Robertson therefore points to the influence of novels like Samuel Richardson’s Clarissa (1747-48), Jean-Jacques Rousseau’s Julie; or, The New Eloise (1761), and Goethe’s The Sorrows of Young Werther (1774), all of which invited readers to empathize with the downtrodden and experience their suffering vicariously. This surge of fellow feeling had demonstrable effects, including an increase in charitable activity, the beginnings of the anti-slavery movement, reforms in the criminal justice system, and even a new concern for the mistreatment of animals.

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Robertson’s facility with literature also allows him to shed new light on the polymathic philosophe Denis Diderot, who seems to be this book’s hero. Typically, Diderot features in intellectual histories as editor of the Encyclopédie, a “systematic dictionary of the sciences, arts, and crafts.” But Robertson also devotes careful attention to literary works like Rameau’s Nephew (1805), the “Supplement to Bougainville’s ‘Voyage’” (1796), and especially D’Alembert’s Dream (1782). Diderot’s fiction shows that great Enlightenment thinkers were more comfortable with human complexity and ambiguity than is typically supposed. “The still-widespread conception of the Enlightenment as a project to erase difference and arrange reality in neat categories…meets its refutation in the work of Diderot,” Robertson observes. Diderot “was interested precisely in those areas of experience that resisted being subsumed under a neat theory.” Though he shared the materialism of his contemporary and fellow encyclopedist Claude Adrien Helvétius, Diderot rejected Helvétius’s unshakable confidence that theory could explain everything. Anyone who reads Diderot’s literary works will recognize his open-mindedness, his acknowledgment of nuance, and his sheer playfulness.

Diderot therefore exemplifies another major enlightenment preoccupation: curiosity. All periods exhibit curiosity about some issues. But the Enlightenment, unlike earlier periods, valued curiosity itself. In late antiquity, Saint Augustine had deemed curiosity a vice. But Immanuel Kant’s famous essay “What Is Enlightenment?” (1784) challenged people to follow their own understanding wherever it might lead. “The motto of enlightenment,” Kant declared, “is…Sapere aude! [Dare to know!] Have courage to use your own understanding!” Perhaps no one lived out this creed more boldly than Diderot. He and his fellow Enlightenment philosophers valued the companionable exchange of ideas in spontaneous conversation as the highest form of discourse. This is one reason Diderot chose the rambling philosophical dialogue as his trademark genre. Enlightenment dialogue is not just an exchange of views, but a collaborative project in which participants open themselves to each other’s points of view. Implicit in this free-ranging, exploratory form is the assumption—not shared universally by intellectuals of preceding periods—that innovation is at least potentially a good thing.

Along with other anti-utopian thinkers like England’s Samuel Johnson, Diderot rejected a popular idea of the time that some formula, even if only in principle, could satisfy human needs once and for all. Utopians imagined man as a finished product, whose needs could be known and satisfied. In reality, he is a being always in process, as Fyodor Dostoevsky would argue forcefully in the following century. According to Robertson, Diderot rejected any view that “required unanimity…[that] assumed that once the clouds of prejudice and superstition had been dispelled, the common good was obvious and undisputable.” To understand humanity, one must recognize what Robertson calls “the inevitable frictions and disagreements among people, which means that society can only progress through conflict, argument, and debate.”

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“Good historians,” Robertson explains, must avoid two opposing fallacies, anachronism and irrelevance. On the one hand, “they must avoid projecting present-day concerns onto a period separated from us by several centuries. The proponents of the Enlightenment…inhabited a very different world from ours and had very different assumptions.” On the other, historians should not put the period into “a historical deep freeze” with no connection to ourselves. “That would be particularly unfortunate in dealing with a movement that still speaks urgently to the present,” when the virtue of tolerating, let alone respecting, opinions different from one’s own is so often disparaged. Consider, for instance, the late Columbia Professor Edward Said’s condemnation of Enlightenment thought as nothing more than a mask for European imperialism. On the one hand, Said denied the possibility that one culture can objectively represent another. On the other, he condemned Europeans for not objectively representing the East. “Every European, in what he could say about the Orient, was…a racist, an imperialist, and almost totally ethnocentric,” wrote Said in his hugely influential book, Orientalism (1978). But if Said was right that it is impossible for there to “be a true representation of anything,” how could Europeans, or anyone else, have avoided ethnocentrism? Are other cultures’ representations of the West and of each other any less ethnocentric? When critics of the Enlightenment insist on viewing the 18th century through a 21st-century lens, it is they who refuse to transcend their own viewpoint in a way that Diderot and Voltaire would have scorned. Other self-righteous critics import into the 18th century a disdain for non-Western cultures more typical of the 19th. As historian Sankar Muthu observed: “It is perhaps by reading popular nineteenth-century political views of progress, nationality, and empire back into the eighteenth century that ‘the Enlightenment’ as a whole has been characterized as a project that ultimately attempted to efface or marginalize difference.”

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In reality, Enlightenment historians were acutely aware of the West’s moral shortcomings at home and abroad. Much as we speak of the Holocaust as the epitome of horrendous wrongdoing, 18th-century thinkers regarded colonial offenses, most notably the Spanish destruction of Central and South American civilizations, as the height of moral atrocity. Robertson devotes considerable attention to a neglected but important work, the History of the Two Indies (1770) by Diderot and another contemporary, Abbé Reynal. At the beginning of Book VII, Diderot is moved to speak in the first person: “I am writing history, and I am writing it with my eyes almost always bathed in tears.” Diderot laments the blind and self-defeating rapacity of Europe’s “fierce warriors” in the strongest possible terms.

Critics have also seen in the Enlightenment seeds of the 19th century’s hostility toward religion. The opposition between science and faith had not yet come into sharp focus, Robertson maintains, besides which Voltaire and others were deists, not atheists. On this point, I do not find the argument entirely convincing. Though deism is in some sense theological, it was regularly presented as an alternative to the religion of the Christian church. Robertson may be right that Voltaire’s mantra “écrasez l’infâme” (destroy the vile thing) was directed primarily at the clergy rather than at religion per se, but the distinction was a fine one and not always drawn. Helvétius, the Baron d’Holbach, La Mettrie and others professed a thoroughgoing materialism with which modern “new atheists” like Richard Dawkins and Christopher Hitchens would have felt at home. And Adam Smith recounted how his good friend Hume remained an atheist to his dying day. Hume even imagined himself negotiating with Charon, who ferries the dead to Hades: “‘[H]ave a little patience only till I have the pleasure of seeing the churches shut up, and the Clergy sent about their business’; but Charon would reply, ‘O you loitering rogue, that won’t happen these two hundred years.’” Robertson is well aware, of course, that French revolutionaries waged a war on Christianity, and that their ideas must have come from somewhere. But he argues that they drew on atypical radicals rather than on the “mainstream Enlightenment”—by which he seems to mean the thinkers that fit his model.

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The quality of Robertson’s analysis declines more sharply when he draws lessons for the present. In contrast to the playful and imaginative Diderot, he seems unable to entertain the possibility that anyone might seriously question progressive orthodoxies. It is one thing to share the clerisy’s perspective, but quite another not even to imagine possible objections to it. For example, one of the Enlightenment’s great contributions to modern thought was the concept of human rights, which are natural, equal, and universal. Robertson notes correctly that although those rights were not extended to most people at the time, the logic of the concept gradually encompassed women, Jews, non-whites, people without property, and others. In his enthusiasm, he then applauds further extensions: “At the present day, a compelling case has been made for the recognition of animal rights, especially in view of the cruelty of factory farming; and the Swiss Federal Ethics Committee on Non-Human Biotechnology advocates recognizing the dignity of plants.” Robertson here confuses the rejection of cruelty to animals with the assertion that they have rights. Kant, the Enlightenment’s most influential moral thinker, would disagree: rights are founded on the capacity to perform one’s moral duty and to acknowledge the rights of others. Animals, let alone plants, do not exhibit such a capacity.

Perhaps most disturbingly, one major implication of Robertson’s argument seems to escape his notice altogether. He can appreciate extending the concept of rights to ferns, but the possibility of extending them to nine-month-old fetuses does not so much as occur to him. Is he unaware that pro-life advocates also appeal to human rights? Or that it might make at least as much sense to extend those rights to viable fetuses, capable of a fully human life and of suffering pain, as to termites and poison ivy? If not, shouldn’t some reason why not be given? Of course, I cannot be sure what he does not consider or why he does not consider it. But I wonder whether the reason for his omission here is that such questions are simply never voiced in academic circles. If so, Robertson is hardly living up to his own ideals: entertaining alternative and unorthodox points of view was precisely what distinguished the Enlightenment thinkers he most admires.

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Similar blindness occludes Robertson’s vision when he discusses religious freedom, which he rightly calls “one of the great achievements of the Enlightenment.” But, he cautions:

[T]his is a precarious achievement (as the history of Northern Ireland in the late twentieth century reminds us), and it could easily be lost. Elsewhere in the world, radical believers like those of Islamic State treat people of different faith as savagely as French Catholics and Protestants treated one another around 1570.

Religious toleration is indeed a delicate and fragile thing. But Robertson’s comparison of Islamic State, which exterminated Yazidis and Christians, with Northern Irish Catholics and Protestants, neither of which ever contemplated exterminating the other, seems aimed less at cogency than at forestalling the charge of Islamophobia. And as a Russia specialist, I am struck by his failure to recognize that in the past century the worst intolerance has not been of one religion against another but of those hostile to all religion against whatever confession happens to be a culture’s traditional one. The “League of the Militant Godless,” and other instruments of Soviet policy, aimed at exterminating Orthodox clergy, ritually desecrating churches, and wiping out the practice of Christianity, Judaism, and (so far as possible) Islam. They went a lot further than anyone in Northern Ireland ever did. Robertson also seems unable to transcend his secular viewpoint enough to recognize that in Europe, and especially in America, hostility to religion has become a sign of political rectitude. This sort of religious intolerance rarely bothers academics.

He complains that “in the Cold War period, it was common to denounce Rousseau as a deplorable prophet of modern totalitarianism.” I wince at the suggestion that complaints about Soviet tyranny and aggression were some sort of right-wing exaggeration. Robertson himself offers good reason for seeing the germs of Soviet totalitarianism in Rousseau when he paraphrases Rousseau’s concept of “the general will”:

There are to be no factions. The assemblies will not debate social issues, but ceremonially celebrate the people’s solidarity. If there is any doubt about what the general will is, magistrates will interpret it for the benefit of the people, whom Rousseau calls “a blind multitude, which often does not know what it wills because it rarely knows what is good for it.”

Substitute “history” for “the general will” and “the Party” for “upright magistrates,” and you have a fair rendition of Soviet doctrine—as the Soviets themselves recognized.

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Though he is no utopian, Robertson cherishes a soft spot for idealists even when, as the French revolutionaries did, they produce disaster. He cites Kant’s idea that “true enthusiasm is always directed exclusively toward the ideal, particularly toward that which is purely moral.” Apologists for what is euphemistically called “the Soviet experiment”—as if the mass murders were a noble piece of social scientific research that somehow didn’t pan out—advance the same defense. How pure were their ideals! Perhaps instead we should conclude that unspeakable danger results from idealistic pursuit of the “purely” moral, especially when it is conducted not with prudent caution and respect for human life, but with “enthusiasm” for the radiant future.

Ritchie Robertson, in short, belies the subtlety of his approach to the Enlightenment by the shallowness of his comments on the Enlightenment’s present-day legacy. But such comments are mercifully few. When he portrays the major figures of the period itself and identifies the complex questions they raised, Robertson transports us to the past as only a master historian can, allowing us to empathize with perspectives different from our own. As a comprehensive study of the period itself, Robertson’s The Enlightenment towers over all others I have encountered.