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Diderot's Encyclopedia

    Denis Diderot's Encyclopédie ou Dictionnaire Raisonné des Sciences, des Arts et  dés Métiers (or Encyclopédie) was a key work of the Enlightenment, an intellectual period noted for the questioning of traditional authority through the use of logic and the emphasis upon empirical as opposed the revealed knowledge. Philosophes, as this group of intellectuals have been named, believed in the experimental method in the pursuit of knowledge, particularly science. They believed that not only the natural world but also human affairs were governed by natural laws discoverable be human endeavor instead of the reliance on supernatural revelations. Although mentioned almost in passing in college survey courses on European history, its influence on Western thought has been significant. Not  only has the modern encyclopedia arisen through it, but it also served as the means through which much of France and part of Europe learned, discussed, and formulated  Enlightenment ideals. Many luminaries or thinkers of the Enlightenment such as  such as Voltaire,  Jean Jacques Rousseau, Montesquieu, Buffon, and Turgot contributed to it, Diderot did the greater part of the  work. The Encyclopédie was his brainchild and his life's work. He directed, and corrected the work of the contributors and wrote most of the articles. Denis Diderot served as general editor of the Encyclopédie . For a time, Jean Le Rond d'Alembert. was an editor. 

    Diderot (1713-1784) was born in Langres, one of seven children of a tool-making family. His brilliance earned him a place in Jesuit  schools as preparation to being a Roman Catholic priest He earned a master's of philosophy degree in 1732 but abandoned the priesthood as a vocation. He studied law in the office of a solicitor in Paris for two years but seemed to have studied everything, including carnal delights, but law. His father discontinued his allowance when it became clear that his son was a freeloader. Forced to support himself, Diderot became a tutor of wealthy children and a translator for ten years. He hated it and eventually quit. He had been doing some hack writing to earn money, an endeavor he then increased to support himself. He also wrote on his own accord. In 1746, he published his Pensées Philosophiques, a controversial work which argue that virtue or a moral life could be lived without religion or religious belief.  He was sent to jail for three months but warned that he could not stop talking about such matters. He had perhaps the most encyclopedic mind that has ever existed. As W.  F. Giese remarked:  "The subtleties of metaphysics, the abstruse problems of mathematics, erudite research, poetry, fine arts and antiquity, to all these widely diversified subjects. his mind turned with equal energy, with equal interest, and with equal facility."(1)

    The  prominent mathematician and scientist, Jean Le Rond d'Alembert (1717-1783)  was born in Paris, the illegitimate son of the French writer Claudine Alexandrine Querinde Tenchin. He was educated at College Mazarin. In 1739, he published his Memoire sur le Calcul Intégral: in 1741, he published Sur la Refraction des Corps Solides. He published his most important scientific work, Traité de Dynamique in 1743, which marked an epoch in the science of mechanics. His Réflexions sur la Cause Generale des Vents (1746) contains the first conception of the calculus of partial differential equations. In 1749, d'Alembert produced the first analytical solution of the precession of the equinoxes. This great mind joined Diderot on the Encyclopédie in 1751, contributing greatly to its articles on science. It was d'Alembert who would recommend Diderot to be general editor of the Encyclopédie

    Diderot was offered the task of editing John Mills' and Gottfried Sellius' French translation of the English Cyclopedia of Ephraim Chambers  in 1746. Chamber's work, published in England in 1728 and represented a growing interest in cataloguing man's knowledge. The first notable encyclopedia of the dictionary type was La Grand Dictionnaire Historique, ou le Melange Curieux de l'Histoire et Profane (1674) of Louis Moréri. Published in English, Spanish, German, and Italian, as well as French, it was a dictionary of history, mythology, and genealogy. Pierre Bayle undertook the task of correcting Moréri's original errors and omissions, and his Dictionnaire Historique et Critique (2 vols., 1695-97) is the most famous work of the 17th century. Chambers expanded Bayle's work. Diderot conceived the idea of an entirely new work which he persuaded a publisher to agree to accept. From its inception, the Encyclopédie was not only a scientific work but also a polemic organ which all the innovators and free thinkers who wished to reform society from political and religious points used for the elaboration of new principles and the destruction of the beliefs of the past. 

    Diderot secured the collaboration of d'Alembert in 1751, but most of the work fell to Diderot himself, who was especially charged with the articles relating to the arts and trades, as well as those to history and ancient philosophy, and who, in addition, undertook the general revision and co-ordination of the material contributed by the others. In form, it was essentially an encyclopedic dictionary, containing both the common words of the language and proper nouns, accompanied by lexical descriptions and definitions, and also, in most cases, by encyclopedic comments. The logical arrangement of the material by subjects was changed to the present alphabetical arrangements by key words, names, or special topics. Its purpose as described in its preface was "... to exhibit as far as possible the order and system of human knowledge, and as dictionnaire raisonné of the sciences, the arts, and trades, to contain the fundamental principles and the most essential details of every science and every art, whether liberal or mechanical." 

    In an essay defining encyclopedia which appeared in Volume V (1755), Diderot sets forth the purpose and the problems of the Encyclopédie. Noting that it could not be the work of a single man, for no one man is capable of knowing everything, Diderot refutes the Jesuit argument that the task would never be completed by saying that time, energy, and genius make impossible tasks possible. 

An encyclopedia ought to make good the failure to execute such a project hitherto, and should encompass not only the fields already covered by the academies, but each and every brand of human knowledge. This is a work that cannot be completed except by a society of men of letters and skilled workmen, each working separately on his own part, but all bound together solely by their zeal for the best interests of the human race and a feeling of mutual good will.(2)

He further states that, as it is only the presence of men that makes the existence of other beings significant, he will seek in man's principal faculties the main divisions within which his work will fall. "For man is the unique starting point, and the end to which everything must finally be related if one wishes to please, to instruct, to move to sympathy, even in the most arid matters and in the driest details."(3) The general tendency to examine life and human knowledge by beginning with God and descending from Him to all lesser beings that have emanated from His bosom in the course of time is defective to a work composed by men of science and addressed to ages to come. It limits and demands too many sacrifices. This fault comes from being too closely tied to theology and to the Church which produces it. Unlike the Church, the Encyclopédie was to examine life from the most important and most logical viewpoint, the position of man. In simpler language, the goal of the many volumes was to find the objective truth about nature and morality without the limitations of religious cant and nonsense, to enlighten humans out of the darkness that Christianity had kept them.

    This incredibly brilliant man with his wide variety of intellectual interests planned to use this media to influence the minds of men. He firmly believed that knowledge in and of itself would correct morals and bring happiness so he was trying to construct his Encyclopédie to contain abstracts of all the knowledge men possessed. Both were reasons he became general editor.

    In the process of collecting and organizing material from other intellectuals (about 100 in all) and from his own work, he became increasingly convinced that the Christian Church was the threat to man. Although he had been a Deist at the publication of Pensées Philosophiques, he had become an atheist. To him, Christianity and the Roman Catholic Church (he never considered the two synonymous) limited man and contributed to ignorance, immorality, and unhappiness. The basic moral problem attacked in its pages is whether there is a natural morality preceding society and the institution of laws, or whether all ideas of morality are the products of society.

    Diderot and his collaborators gave an affirmative answer to the first question, excluding a religious basis for morality or any innate moral ideas, and seeing man as a part of nature. It followed that natural morality could be discovered from a study of the facts, and should be scientific, positive, and sociological. In practice, however, the philosophes made no empirical inquiries; they ignored the mass of information that existed on the social customs of the various people of the world. They tended to discredit anything they could not understand as a product of human folly or roguery, especially priest craft. Their belief in a natural morality was a belief in a theoretical pattern, of universal validity which merely needed to be discovered to be applied. 

    Diderot, however, saw the difficulty into which this position led one, for human behavior has fantastic varieties. With such a philosophy permeating its pages, it is no surprise that the Encyclopédie met clerical and royal opposition. Twice, in 1752 and in 1757, Diderot's opponents succeeded in revoking the royal decree granting permission for the work to proceed. D'Alembert withdrew from the editorship in 1758, because the government interfered with its publication, but he continued to contribute articles. 

    As the broadest and most reliable systematization of contemporary knowledge that had yet appeared, Diderot's encyclopedia achieved a tremendous popularity among the literate, so much so that it provoked the King's Council in 1759, to suppress the first seven volumes, and forbid further publication. Diderot had already undergone persecution through suspensions of printing and threats of imprisonment, but he continued to work on the ten remaining volumes. At the last moment came the bitterest trial of all, the publisher had mutilated these volumes by suppressing whatever might be offensive. They appeared in 1765, and were a very great success. Its four thousand subscribers (who had supported Diderot in his time of troubles) were all people of means and often of rank, miscellaneous supplements continued to be published until 1780. 

    Diderot refused to make the Encyclopédie  a single immense pamphlet in the interest of reform as some zealots of the Enlightenment urged him. While some biased and subjective articles were slipped in, the specialists, under Diderot's direction, handled the subjects assigned to them in an objective manner trying to create an honest work of general information. Diderot, however, had declared war on organized religion, and, with royalist attempts at suppression, the tone of the Encyclopédie had turned against royalty. Through the efforts of Choiseul, the foreign minister, and Madame de Pompadour, the king's mistress, the attempts to suppress free inquiry and "enlightenment" had been stopped, but the work remained controversial as well as excellent. 

    Systematically, the Encyclopedists examined every phase of life and every institution. The right to do so was sacred to them, and much that they found through their examinations was blasphemous to their prevailing ideas. For example, Francois Quesnay (1694-1774), in the articles he wrote for the Encyclopédie, attacked mercantilist economic policy so popular among conservatives. He claimed that men could discover natural economic laws "susceptible of a demonstration as severe and incontestable as those of geometry and algebra." He said that land was the only source of wealth and that agriculture increases wealth. He believed in and preached laissez-faire; the state should not interfere with the free play of natural economic forces, and especially not private property which he considered necessary for the production of agricultural wealth. One of the progenitors of free enterprise thought, he, like others, believed that immutable natural laws governed human affairs and all attempts to thwart them created havoc and misery. 

    On another issue, the philosophes believed that societies and governments should let nature take its course for man-made legislation prevented the application of the natural laws of justice. They disputed and scorned the ancien regime and its judicial system. Legal codes needed to be humanized and simplified, arid a new science was needed to make the punishment of crime both humane and effective. Punishments should aim to prevent the criminal from doing further damage to society and to prevent others from committing the same or similar crimes. Causes should be discovered and then remedied. Torture and capital punishment diverged from natural laws. Justice should act speedily to reinforce the association between crime and punishment. Crimes could be more effectively prevented by the certainty of punishment rather than the severity of punishment. The Encyclopedists felt that the best way of preventing crime was to perfect the system of education. 

    The belief in education brought the school systems under attack. The old regime failed to pass the tests of reason and natural law. The widespread ecclesiastical control of schools and universities as well as the curriculum--theology, Greek, Latin, and ancient history-- were deplored. They demanded more science, modern languages, and modern history. The Encyclopedists believed that to educate a nation was to civilize it, and that education gives dignity to man. They preached reforms, and their efforts resulted in the treatment of children as children rather than as miniature adults, a reform which has had serious consequences. 

    Their attack on the clergy was combined initially with their attack upon education. The clergy, they claimed, were teaching superstition and religious fanaticism, thereby decreasing and limiting the value of the human. The Encyclopedists tended to view God as the master weaver, or, since the Newtonian world machine implied a mechanic, a clock maker. God invented this intricate world, giving it natural order and law, and then sat back and watched it. He did not answer prayers or extend grace, for the world was not totally arbitrary and capricious as the belief in divine intervention required. Organized religion, seeking the prosperity and well-being of its leaders, clouded men's minds and bound them in chains of superstition. 

    Diderot substituted the cult of nature for the fervor of religion. He anticipated many of the details of Darwin's evolutionary theory. He was one of the first to offer a comprehensive and really scientific theory of the universe on purely materialistic grounds. He substituted the word happiness for the word duty. In spite of eloquent insistence on morality and an infinite deal of sentimentalizing on the charms of virtue, his ethics are epicurean. Instinct and passion are exalted into the sole guides of conduct. This is the reappearance of the pagan ideal of the Renaissance armed with a scientific and skeptical philosophy. 

    The Encyclopedists and their work can be traced backwards to the seventeenth century and, from there, back to the Renaissance. What they believed was a new humanism, a new stress on the importance of man. This time they succeeded in placing man as the center of the world; they managed to lead a successful attack on established religion and established institutions. The secularization of society which tended to occur in this period emanated from the work of the Encyclopedists. On the other hand, the beginnings of the reaction against their deism could be seen in the Methodist movement in England, the Pietist movement in Germany, the continuance of the Jansenist and the Molinist movements in France, and the beginning of the Great Awakening in the British North American colonies. Freedom of inquiry had been established as an ideal and a right. Despotism was wrong, unless it was enlightened, for the good of the people, promoting the ideals of the Encyclopedists. This new humanism had far reaching effects: the later humanitarianism grew out of the Enlightenment, and the early and immediate romantic movement began before the Enlightenment had ceased. 

     Diderot, the incarnation of the Enlightenment, had turned what was to have been an edited translation of an encyclopedia into a major work in the history of man both as a modern encyclopedia and a vast, strong, and popular propaganda media. His talents guided the course of the Enlightenment 

    The Encyclopédie was largely instrumental in leading the nobility and the ruling classes to imbibe that philosophy of liberalism which was to prove their destruction. It was a middle class sponsored and absorbed work for the most part. Its ideals became commonplace, especially vocalized by the middle class. The Encyclopedists greatly influenced American thinks and politicians such as George Washington, Thomas Jefferson, Benjamin Franklin, and John Adams who founded the United States upon liberal principles. A few years later in the cahiers and documents of the French Revolution, their ideals, their attacks upon established authority, and their rebellious spirit certainly pioneered the emotions which produced the Revolution. 

    The Enlightenment had arisen through the rise of science and the experimental method, the writings of Locke, and others who stressed the rational process and the importance of man, and a disenchantment with a dysfunctional established order, but this collection of ideas and protocols for learning was only the concern of a small educated elite; the average person, who was illiterate and ignorant, would not have heard the ideas or understood them. Instead, they believed what they were told by people in authority and rarely had the luxury of the slow, systematic analysis of events. Emotion, tradition, fear, and religion controlled their lives not logic and objective evidence. In their hearts, they knew they were right, to paraphrase a mid-20th century US politician. Although the liberal ideals of the Enlightenment, of the Encyclopédie, persist, romanticism became the leading philosophy and attitude. Nevertheless, the modern world stems from the Enlightenment.


1. W.  F. Giese, Selections from Diderot. Chicago (1908). p. 10. 

2. Denis Diderot, Rameau's Nephew and Other Works. Garden City, New York (1956), p. 298. 

3. Ibid. p. 308.

Don Mabry