Visions of Unlimited Progress: Denis Diderot and the Encyclopedia of the French Philosophes

All kinds of Enlightenment events occurred before 1715 and after 1789, but those dates tend to prevail because they are French. The most credible explanation for this is the monumental French Encyclopedia and the circle of intellectuals, the French philosophes, who formed and were active around it. It became their common purpose and their inspiration: to further knowledge for all people and, by this “enlightenment,” to deal a deathblow to what they viewed as reactionary forces of church and state. I will deal, here, with the man who against all odds exploded the original scope of the project (initially a translation of another dictionary); carried it forward (1745–1772) against obstacles of poverty, censorship, and imprisonment; and himself wrote thousands of entries as collaborators withdrew from the project out of fear.

Denis Diderot (17131784)

Denis Diderot, born in 1713 in Langres, a medieval fortress city in eastern France, where today there is a statue of him, emerged metaphorically from the shadows of medieval France into our modern world. Educated by Jesuits, but pulling back twice from an ecclesiastical career, he ended up a materialist atheist. 

His upbringing and education—to say the least—did not define for him a clear path into this new world. He looms large in history but remarkably little is known about the years before he undertook the Encyclopedia. He studied in Paris for three or four years starting in 1729; it is not certain where, but the University of Paris awarded him a Master of Arts degree in 1732. For a while, he studied for law, but his interests lay in literature, philosophy, and science. Then, there are ten years of his life in Paris that are at the very best sketchy.

Theater, teaching, and the priesthood all seem to have been sampled, but his works reveal that he experienced a religious crisis that took him stepwise from his Roman Catholic upbringing and education to deism to atheism. This was the progress, in one man, of the Enlightenment at large.

A novel published only after his death, Rameau’s Nephew, reveals a chaotic bohemian existence in the Parisian coffeehouses, where he met Jean-Jacques Rousseau. At this time, also, he married Anne-Antoinette Champion (in secret because of his father’s opposition) and had a daughter, Marie-Angélique Champion, who engaged Diderot’s care and his devoted attention to her education. 

By 1745, he was eking out a living by writing for hire. He translated the famous Inquiry Concerning Virtue by Anthony Ashley Cooper, third Earl of Shaftesbury, whose influence, including in France, was enormous. Diderot also published his own original work, Philosophic Thoughts, with impassioned rhetoric espousing anti-Christian ideas—not surprisingly influenced by passages from his translation of Shaftesbury.

Diderot’s Conception of the Encyclopedia 

At this time, the Encyclopedia had come into his life but did not yet dominate it as it would later. Its publisher, Andre Le Breton, had been seeking a French translation of Ephraim Chambers’s encyclopedia but had been turned down several times. Diderot accepted the task that shaped the rest of his life, his place in history, and the course of the Enlightenment itself. 

As a coeditor, Diderot had the renowned Enlightenment mathematician Jean Le Rond d’Alembert. By this time (1745), Diderot was an advocate of Enlightenment ideas and transformed the mission and scope of the Encyclopedia to make it an organ of radical and revolutionary ideas.  To this project, as he had defined it, he was able to attract men in literature, science, and even religion, many unknown then but destined to become well known indeed.

The Encyclopedia (subtitled: “systematic dictionary of the sciences, arts, and crafts”) finally ran to twenty-eight volumes of text and plates comprising more than 70,000 articles by some 140 contributors. The tireless Chevalier Louis de Jaucourt (1704–1780) wrote about 18,000 articles on political topics, going far toward solidifying the new political teachings of the natural-law tradition. Diderot and his colleagues came to conceive the work as transmitting existing human knowledge to later generations. The consequent progress of knowledge and its dissemination would underwrite the positive transformation of society. 

The perspective of the work is resolutely secular and implicitly antiauthoritarian. That provoked the censors of the French state of the ancien régime—a headwind that Diderot fought for years to complete the Encyclopedia. But the state’s opposition did bind together the wide variety of French intellectuals who were Diderot’s collaborators with a shared sense of purpose.

The knowledge and “voice” of the Encyclopedia are social (the title page refers to a “a society of men of letters”)—intended to educate and thereby improve society “so that our offspring, becoming better instructed, will at the same time become more virtuous and happy, and that we should not die without having rendered a service to the human race in the future years to come.” Its entries range over all knowledge and do so at levels from the most abstract to the most practical (mechanical and technical). In that, the Encyclopedia reflects the Baconian concept of what is susceptible to the application of the scientific method (more or less everything). In each case, the topics are addressed in the context of the Enlightenment: science, metaphysics, epistemology, rationalism, empiricism, skepticism, the science of man, political theory, the nature of the good, religion, the beautiful in aesthetics, French classicism versus German rationalism, and the relationship between empiricism and subjectivism. (Here is an anthology of selected political entries from the twenty-million-word Encyclopedia.)

Thus, the new goal set for the Encyclopedia by Diderot was to be a “rational dictionary,” an encyclopedia of the essential principles and the manifold applications of every art and science. The philosophical foundation could be said to be rationalism, the foundational epistemology of the early Enlightenment only later to be qualified by empiricism.  

The Long Battle to Survive and to Finish

At this time, Diderot became outspoken on the doctrine of materialist atheism, arguing that humans depend for all knowledge on sense impression—an epistemology that precludes revelation. (“If you want me to believe in God, you must make me touch him.”) The answer of the French government was to arrest Diderot and imprison him in Vincennes for three months. It was a mere pause for Diderot.  

From the inception of the Encyclopedia in 1745, to publication of the first volume in 1751, to distribution of later volumes of plates in 1772, Diderot fought government censorship, criticism by the establishment conservatives, and the resignation of d’Alembert out of fear of trouble. Diderot did not seem to doubt, but he reported himself shocked and hurt when he discovered that the publisher, Le Breton, had taken it upon himself to excise what he deemed compromising passages. Historians comment that the censored passages, although of interest, really did not lessen the work’s impact. (They now have been published as the “eighteenth volume” of the Encyclopedia.)

Diderot not only was general editor of the seventeen volumes of text but also supervisor of the illustrations for some 3,000 to 4,000 plates. And so, one hard-fought volume after another, the monumental work was completed.

For some years, he was sustained financially by Catherine the Great of Russia, a fervent admirer and correspondent of Voltaire and other Enlightenment intellectuals, and an example of an “absolutist champion” of the Enlightenment. Among other things, she purchased Diderot’s library for a handsome sum but told him to keep it for her in France. 

In 1784, just two years after completion of the Encyclopedia, and five years before the onset of the French Revolution in 1789, Diderot died. He did not live to see the overthrow of the ancien régime of which he dreamed most of his life—nor later witness “Paris gone mad” with the Terror and the violent reaction that followed. But would he have been surprised? One famous quotation: “Men will never be free until the last king is strangled with the entrails of the last priest.” 

William Bristow writes in the Stanford Encyclopedia of Philosophy:

“The energy created and expressed by the intellectual foment of Enlightenment thinkers contributes to the growing wave of social unrest in France in the eighteenth century. The social unrest comes to a head in the violent political upheaval which sweeps away the traditionally and hierarchically structured ancien régime (the monarchy, the privileges of the nobility, the political power of the Catholic Church) . . . the devolution of the French Revolution into the Terror in the 1790s, corresponding, as it roughly does, with the end of the eighteenth century and the rise of opposed movements . . . can serve as a convenient marker of the end of the Enlightenment.”

It was indeed an obvious historical demarcation, but not so much of the end of Enlightenment intellectual achievements, which continued for decades, but of the Enlightenment as a confident movement looking forward to an ever-improving human condition and society.