Wherever we look today in academia, scholars are rushing to defend the Enlightenment ideas of political and individual liberty, human rights, faith in scientific reason, secularism, and the freedom of public debate. Why the worry? These ideas are, after all, enshrined in the U.S. Constitution. And yet, to hear the defenders of the Enlightenment, they are under assault. There is no shortage of enemies—from mullahs and Christian conservatives to science deniers and left-wing post-modernists.

Defending the Enlightenment has become an academic cottage industry with various camps hunkering down behind their own interpretations, and, in good academic form, attacking others. But recently, a few leading scholars have decided that it was necessary to present their defenses to a wider audience. Lynn Hunt’s Inventing Human Rights: A History (2007) was one of the first of such works; her argument made the case for Enlightenment values and the “soft power of humanity” in light of the use of torture by the U.S. government, but also, implicitly, because of the rise of new superpowers, like China, which openly reject human rights while embracing scientific progress. In The Enlightenment: And Why It Still Matters (2013), Anthony Pagden traced a history of Enlightenment philosophy, defending it from “theocracies” and the “fringe of the Christian right” that deny ideas of scientific progress, political liberty, and “global justice.”

These books—and the overall defense—have some validity. In spite of the fact that the U.S. Constitution and Bill of Rights were founded on Enlightenment ideas, it is not clear how many Americans understand the relationship of the Enlightenment to such documents. Many deists—believers in the Enlightenment idea of a post-Christian mechanistic nature god, such as Founding Fathers Thomas Jefferson, Thomas Paine, and Ethan Allen—would, with their scorn of organized religion, have a hard time getting elected in most parts of the United States today. The abolition of torture and capital punishment, seen by John Adams and Jefferson as central to Enlightened society, is now political anathema in most of the United States. Even the scientific explanation of natural phenomena is generally rejected or ignored, with only 40 percent of Americans standing by the scientific finding that global warming is man-made. When George W. Bush won the 2004 election, Gary Wills characterized the victory as “the day the Enlightenment went out.” The ideas of the Enlightenment are going through a crisis in the very country founded on them.

All this makes Vincenzo Ferrone’s newly translated book, The Enlightenment: History of an Idea, compelling: Ferrone claims that the importance of the Enlightenment has not been its triumph, but its centrality in public debate. An Italian historian of philosophy and a specialist on the influence of Isaac Newton, Ferrone believes the Enlightenment must be defended not simply as a secular, political idea, but, most importantly, as what Ferrone calls a tradition of “critical thought.” Immanuel Kant defined the Enlightenment as the “progress of mankind toward improvement” through the “freedom to make public use of one’s reason on every point,” and Ferrone claims it is this critical process that has driven public opinion and politics, giving us the language of human rights, tolerance, and individual liberty. The long philosophical engagement with the idea of Enlightenment, from Voltaire in the eighteenth century down to our own time, is, for Ferrone, one of the great intellectual legacies of the Enlightenment itself. He allows that we can question the primacy of science and secularism, but not critical debate. Many great figures of philosophy who have been seen as critics of the Enlightenment are in fact, Ferrone argues, defenders of the Enlightenment tradition.


The Enlightenment began not only with books and pamphlets, but with an earthquake. In 1755, an earthquake flattened Lisbon, set it aflame, and then caused a massive tsunami that swept the Tagus River into the city, killing more than 40,000 people. Theologians claimed the disaster was divine retribution for earthly pride and sin.

The French philosopher Voltaire argued, though, that it was simply nature’s systems that had caused the movement of the earth’s crusts. He criticized the Catholic Church for claiming God was behind the disaster rather than the clock-maker master of the system of nature. Voltaire’s opinion led to a famous international debate that helped him move public opinion away from mystical explanations of natural phenomena and toward scientific authority.

Ferrone’s model of an Enlightenment tradition comes directly from Voltaire. He was one of the first to recognize the Enlightenment as a distinct movement; he used the word lumières to describe philosophers seeking progress through criticism, and claimed that the new gens de lettres, or “men of letters,” were super-scholars who, as living encyclopedias, would master the arts, sciences, and, above all, literature. These enlightened ones had a primarily social function: to critique in the name of progress. Kant summed up Voltaire’s idea best when he said: “Our age is the age of criticism to which all must be subjected.” The ultimate goal of this critical movement was to create reason for the betterment of society, and this reason would have to stand the “test of free and public examination,” Kant said.

At least on the level of creating a critical tradition, the Enlightenment project worked. Books, pamphlets, journals, and papers proliferated during the eighteenth century, and public debate, in turn, created public opinion that began to stand as a counterauthority to kings, religious leaders, and states. The great philosophers who followed Voltaire and Kant—Hegel and Nietzsche in particular—might have questioned secularism, the power of science, and human agency, but they always defended an ideal of criticism.

Writing in the early nineteenth century, Hegel grappled with the Enlightenment as a critic, not a proponent. The idea of secular human progress, Hegel warned, was misguided in attempting to bring “heaven” to the “earth below.” Hegel felt that this hubris, as well as the loss of all Christian morality and the belief that humans could build a secular paradise, had brought about the Terror of the French Revolution. But he still saw the Enlightenment as the central point of a philosophical inquiry steeped in skepticism and an abiding belief in criticism. If one was to study human history, Hegel warned, one could never be “passive,” for historians came with their own predetermined “categories.” Only through the constant critique of subjectivity and through dialectic argument could humans face the challenges of earthly reason and science. It is this skepticism and method of criticism of the Enlightenment itself, Ferrone claims, that makes Hegel—the critic of progress and secularism—an Enlightenment thinker.

Like Hegel, Nietzsche was skeptical of the Enlightenment claims of progress and human utopia. Through an examination of the Renaissance and Reformation, Nietzsche replaced the idea of progress—which he thought “primitive” Germans, at least, could never grasp—with his idea of the modern man’s “will to power.” If Nietzsche embraced Voltaire as the great debunker of religion, he nonetheless believed that secularism did not lead to the betterment of humankind, but instead opened the door to nihilism. Ferrone, on the other hand, presents Nietzsche as one of the guardians of the Enlightenment. Nietzsche embraced Kant’s question, “What is Enlightenment?” as the inspiration of his own philosophical progress. And even if nihilism contradicted the optimism of the Enlightenment, it still adopted a model of human rather than divinely inspired destiny, and for this, Ferrone claims, Nietzsche held the “banner of Enlightenment.” This human destiny, no matter how dark, would be attained through the criticism of the illusions of both Christians and socialists.


The Enlightenment faced perhaps its biggest challenge following the Holocaust and Hiroshima as philosophers were forced to question ever more deeply the idea of human progress. Even those who believed in science now had to come to grips with the idea that it could be used as a tool of mass extermination. On the one hand, the Enlightenment could bring human progress through science, public debate, and a rational, social state. On the other hand, these very forces—along with a twisted idea of progress, and Nietzsche’s will to power—had been at the heart of Nazi power and its ideology. The Nazis, warned German-Jewish philosophers Max Horkheimer and Theodor Adorno, had reduced and “dehumanized” Enlightenment aspirations, and they had turned science into “manipulation and administration” and reason into a nihilistic scientific program of mass death. Enlightenment, they warned, could bring liberty, but also a modern totalitarian system. What the Nazis had done was to take Enlightenment discourses and rid them of their critical element. The outcome was disastrous. Without the culture of criticism, Hegel’s skeptical vision was realized, and only terror reigned.

French philosopher Michel Foucault also reflected on the Enlightenment and its pitfalls as a science of humanity in his famous lecture, “What is Critique?—Critique and Enlightenment.” In the tradition of Nietzsche, Foucault criticized modern scientific and legal authority, as well as the entire Western system of sexual and social norms, not as the product of a reasonable society, but as systems of power. By studying hospitals, asylums, and prisons, Foucault showed the underbelly of enlightened societies, and how institutions of so-called modern reason could be turned into instruments of repression. In spite of this ambivalence, he still felt a need to engage with the Enlightenment by paring it down to the constant and unrelenting critique of power itself. Critique, Foucault insisted, is the movement by which individuals question all truths, especially those produced by powerful authorities.

Where are the debates of the Enlightenment taking place today? Foucault’s critique of power left many who read his work skeptical of Enlightenment ideas of progress. This, in turn, has led to fierce academic debates, but ones that take place less and less in the realm of mass public opinion. The university debate, Ferrone argues, is central to the continuation of the Enlightenment tradition. But Ferrone has inflated the importance of modern historical works on the Enlightenment; their engagement with the Enlightenment does not occupy the central stage of public debate and opinion-making. Enlightenment ideals were central driving points of the American Revolution. Yet what U.S. politician campaigns by defending the ideals of the Enlightenment?

The place of the Enlightenment in public debate has all but disappeared. Renowned philosophers who do engage with criticism of the Enlightenment, such as Jürgen Habermas and Charles Taylor, do not catch the imagination of a wide public in the way Foucault did 40 years ago. Even the great scientists of NASA and Caltech, heirs of Isaac Newton, armed with massive modern reams of data, cannot sway the majority of the American public into believing that global warming is man-made. Instead of major philosophers, entertainers like Bill Nye and Ken Ham debate evolution at the Creation Museum (a museum that asserts the world came about in a strict biblical chronology), with many in the audience applauding the creationist.

If science is contested, the Enlightenment, it seems, has become a relic. And yet the Enlightenment is not forgotten everywhere. As Ferrone notes, Pope Benedict XVI has spoken numerous times about the Enlightenment as an ongoing challenge to the Catholic Church. Indeed, Benedict debated the idea of the Enlightenment with Habermas in a work called “The Dialectics of Secularization” when he was still Joseph Ratzinger—the first time a future pope has sat down with a modern philosopher to discuss the Enlightenment. Not surprisingly, Benedict regrets many secular values and nonreligious government, yet at the same time he speaks of the importance of the Enlightenment in bringing individuals the freedom to believe and in asserting human rights in a global society. This doesn’t make Benedict an Enlightenment philosopher, but it does make him the most influential world figure to engage in the old dialectic.

We are thus faced with a stunning paradox in the history of Enlightenment debate. As the Enlightenment recedes from public consciousness, the original foe of Voltaire, the Catholic Church, engages with the idea of Enlightenment more prominently than many secular thinkers. Ferrone worries that this is a “muddying of the waters” of the Enlightenment debate. Yet Ferrone does not seem to recognize the challenges and paradoxes that face the idea of Enlightenment in a world disengaged from it.

If anything, Ferrone unintentionally shows that the old secular model of progress is failing, or has evolved in a world that embraces its products but not its central idea. If the Enlightenment is to survive, its proponents must fight apathy along with enemies. The public takes for granted complex debate and is often disconnected from the arguments of the informed press. This was not the case in the past, when the advocates of Enlightenment ideas and criticism were able to muster the passions of large populations. It is clear, though, that the Enlightenment will need great champions as well as critics to revive the debate that is its internal motor. For the moment, with critics of the Enlightenment the most engaged debaters, this looks unlikely.