Denis Diderot (2578 words)

David J. Adams (University of Manchester)
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Denis Diderot was born, the son of a cutler, in Langres in Champagne on 5 October 1713, and died in Paris on 31 July 1784. He is one of the most original figures of the French Enlightenment, and also, in some ways, one of the most intriguing. Much of his early life, unlike that of equally famous contemporaries such as Jean-Jacques Rousseau or Voltaire, is shrouded in mystery. Many of the works which he published during his lifetime were anonymous, or were ascribed to other writers, and even today his role in their composition is not always clear. Some of the works for which he is now most noted appeared many years after his death. During his lifetime, his most often reprinted works were two plays, though they were hardly ever performed. Until the twentieth century, his name was anathema to much of the French intellectual and ecclesiastical establishment. Even now, he remains a complex and controversial figure, whose contribution to fields as diverse as epistemology, political theory, religious polemic, anti-colonialism, the theatre and the novel mark him out as one of the most distinctive French writers of the last three centuries.

Both his younger brother and a sister entered the Church, and Diderot himself went to Paris in 1729 to study theology. He took a master’s degree in 1732, but at some point thereafter he abandoned his religious studies to devote himself to a variety of intellectual pursuits which included mathematics, chemistry and modern languages. For some ten years, he seems to have led a hand-to-mouth existence as a tutor, translator and hack journalist. He gradually lost whatever Christian faith he previously had, and began moving towards a materialist position, which led him to take the view that matter is the only entity in the universe, and is governed by laws which we understand only imperfectly. These ideas were at the core of much of his thinking over the next few years.

His views are vigorously expressed in his first independent work, the Pensées philosophiques [Philosophical Thoughts] of 1746. He asserts that the universe may have been created by God, but may also be the product of a chance amalgam of atoms, thrown together in a random order which may be merely temporary. He is also aware that moral behaviour may be a product of stern laws rather than any innate human goodness, a point to which he was subsequently to devote much more reflection. The “natural religion” outlined in the Thoughts is intended to rally believers of every kind to worship a god whose precise attributes are unimportant.

Although the book was immediately condemned by the authorities, it made Diderot’s reputation as a free-thinker and a formidable writer. As someone with a wide range of interests, he was hired, with the eminent mathematician D’Alembert, as one of editors of the great Encyclopédie ou Dictionnaire raisonné des Sciences, des Arts et des Métiers [Encyclopedia] (q.v.) which was to occupy most of his time for nearly twenty-five years, from 1748 to 1772

With its emphasis on the importance of the mechanical arts, and its veiled criticisms of the inequities of contemporary France, the Encyclopédie was to become arguably the most representative work of the French Enlightenment. Yet, despite his Herculean efforts as co-editor of (and a major contributor to) this massive undertaking, Diderot continued to publish works on his own behalf which show his originality and intellectual vigour in a variety of fields. Each of the books which he published in the period 1748-1754, in particular, marked a new departure in his exploration of three major questions: what can we know, how can we know it, and how certain is our knowledge?

To the first of these problems, he initially believed that mathematics provided the answer. His Mémoires sur différents sujets de mathématiques [Memoirs on various mathematical subjects] (1748) shows Diderot’s technical mastery of a subject which was to form the basis of his Lettre sur les Aveugles [Letter on the Blind] (1749). The blind mathematician Saunderson uses a system of pins arranged to enable him to perform calculations, and to communicate with others via the language of mathematics. Yet the blind have a different moral sense from the sighted: they hate theft, but they are indifferent to nakedness. Thus, morality depends on our senses, rather than on absolute fixed imperatives, and belief in the goodness of God may not come easily to a man deprived of sight. As Saunderson observes on his death-bed to a minister of religion: “If you want me to believe in God, you must make me touch Him”.

In 1751, with his Lettre sur les Sourds et Muets [Letter on the Deaf and Dumb], he argues that the subject-verb-object order is inherent in all languages, and corresponds to the way in which we actually see the world. Hence, all human minds work in essentially the same way, processing perceptions into language in ways which are universal. This second Letter is a half-way point between a belief in the capacity of man-made systems, such as mathematics or language, to lead us to true knowledge, and the idea that the world exists outside ourselves, waiting to be discovered. Thereafter, Diderot’s initial faith in mathematics was gradually overtaken by a belief in experimental science. There are traces of this view even in his early pornographic novel Les Bijoux indiscrets [The Indiscreet Jewels] (1748), but it gradually becomes central to his thinking, as we see in the Pensées sur l’interprétation de la nature [Thoughts on the interpretation of nature] of 1753-54.

The Interpretation has some claim to being an Encyclopédie in miniature: in both cases the scientific inspiration derives ultimately from the work of the English philosopher and statesman Francis Bacon; both works emphasise that knowledge should be used for the benefit of mankind; both stress the need to understand and interpret nature for those who are not necessarily experts, and both state that such understanding can be achieved through the testing of hypotheses. More than in his previous works, Diderot believes that matter operates according to regular, intelligible laws, even if species may alter over time in ways we do not yet understand; perhaps matter which appears to be dead may gradually be transformed into a living entity, and vice versa; ultimately, the study of nature needs to be undertaken sub specie æternitatis, and with no strict boundaries between one form of matter, or one entity, and another.

Several of his writings from the 1748-54 period emphasise also the collaborative nature of intellectual investigation. Even in the Letter on the Blind, we see men working together to discover the truth through the use of the agreed symbolism of mathematics, and of course the Encyclopédie was a collective enterprise par excellence. In the Suite de l’Apologie de l’abbé de Prades [Afterword to the Apology by the abbé de Prades] written in 1752 to defend one of the contributors to the Encyclopédie against charges of atheism, Diderot argued that human beings are social creatures, who function best when they live and work together, and for whom prolonged solitude is unnatural. This view may well have been strengthened by the three very sobering months he spent as a prisoner in the fortress of Vincennes in 1749, for having offended Church and State with his writings.

Building on his view that intellectual endeavour should bring people together, Diderot’s works from the mid-1750s onwards are concerned, in one way or another, with relations between human beings, rather than with purely philosophical or epistemological questions. His two plays Le Fils naturel [The Natural Son] (1757) and Le Père de famille [The Father of a Family] (1758) owe much to the drame bourgeois [middle-class drama] which had existed for some years in France, but which he did much to develop in theoretical terms. His aim is to portray “conditions”, that is, characters placed in carefully-delineated social, family and personal situations, in order to test their strength of character and their moral sense when faced by powerful emotional conflicts. The plays might thus be regarded as human experiments which complement the scientific investigations of the Interpretation. They also push to new limits the dividing line between “representation” and “reality”, as though these boundaries were as fluid as those separating one species from another. In both cases (and in other plays which he wrote, but which remained unpublished during his lifetime), Diderot underscores the importance of the family as the setting for the drama, and it is the strength of the family which reasserts itself through all the emotional vicissitudes of the action.

This emphasis on emotion, and on the need for the artist to render it truthfully and forcefully, is apparent also in the art criticism, the Salons which Diderot began to write in 1759 and which he continued until 1781. This principle, and a concern for the consequences of the breakdown of the family, informs his novel La Religieuse [The Nun] (c.1760). This is, in part at least, the study of dysfunctional human relations. Rejected by her family because she is illegitimate, and forced to become a nun, Suzanne Simonin discovers that cruelty, rivalry and sexual deviation are commonplace in convents, because the life there is an artificial one, isolated from normal society. Here, too, Diderot continues to enlarge the boundaries of the conventional novel by creating a series of fictional letters from “Suzanne” to a genuine correspondent, the Marquis de Croismare, thereby blurring the distinction between truth and fiction. This process is used to equally striking effect in later writings, such as Le Neveu de Rameau [Rameau’s Nephew] (1762-72), Le Rêve de D’Alembert [D’Alembert’s Dream] (1769), and Jacques le fataliste [Jacques the Fatalist] (c.1770), all of which, like The Nun, were published long after his death. While the range of topics covered in these works (which are largely in the dialogue form which he preferred) is very wide, they are linked by the presence of the author as a character in each of them, and by the presence, in the first two, of interlocutors whom Diderot had known personally. In Rameau’s Nephew, the narrator (identified only as “I”) acts as a rather conventional, staid foil for Rameau (“He”) who argues that he cannot help his penchant for vice and immorality, since that is his nature, which is the product of his “molecules”. This basically materialist thesis is the background for the discussion of topics as varied as the nature of creativity, the role of morality in education, and the relationship between society and the individual. The work allowed Diderot to express, in secret, ideas which troubled him greatly. If we are the product of our physiology, punishment is pointless, and vice and virtue are meaningless categories. Indeed, at one point Rameau observes: “If we got down to explaining our ideas on the subject, it might turn out that you called virtue what I call vice, and vice what I call virtue.” Although the narrator believes that punishment and social ostracism can act as a deterrent to misbehaviour, Rameau’s own example casts doubt on the validity of this view, and the work ends inconclusively.

The materialism of Rameau’s Nephew is explored further in D’Alembert’s Dream, in which the character of Diderot’s former Encyclopédie colleague argues that the distinction between “dead” and “living” matter is illusory (thus answering the question raised in the Interpretation, and showing Diderot’s tendency to return throughout his life to problems which preoccupied him). All creation consists of the same matter which constantly takes new forms, and the “mind-body” dualism described by Descartes is an error. Human beings are not essentially distinct from other forms of matter, and what we call the “soul” is no more than the centre of our consciousness. Such views (and the unflattering presentation of D’Alembert and other close acquaintances) made the work impossible to publish (it finally saw the light of day in 1831). However, they also underlie much of his novel “Jacques the fatalist” (published in 1796) which, while mocking the artificiality of the novel convention, examines, inter alia, the question of free-will, and the responsibility we have for our own actions. Though Jacques denies that man has free-will, and maintains that our fate is written on the great scroll of destiny, human freedom is exemplified by the very way in which the narrator recounts his story. Yet Diderot’s interest lies no less in exploring the instability of human affairs, and the emotional basis of our behaviour. These concerns are best illustrated in the story of the jilted Mme de La Pommeraye, who takes pitiless (and ultimately futile) revenge on her former lover the Marquis des Arcis, blaming him for ceasing to love her while ignoring the fact that our material nature is not made to remain always the same. In choosing to concentrate on such behaviour, and on that of the utterly immoral père Hudson, Diderot continues the exploration, begun in the Nephew, of characters who behave with complete selfishness, and who depart knowingly from social convention with no scruple or compunction. His concern now, however, is less with the causes than with the effects of such conduct, and here too we can find links with preoccupations which appear in earlier works. These links derive principally from his ideas on politics and on the principles of social organisation, in that he is both fascinated and repelled by great cruelty. His hatred of repression and tyranny runs through much of his writing almost until his death, along with his advocacy of materialism and his concern for the welfare of man as a social being. Diderot was opposed as much to the tyranny of the Catholic Church as to that of despots, and his most trenchant criticisms of its effects on sexual morality and social mores are to be found in the Supplément au voyage de Bougainville [Supplement to Bougainville’s Voyage] (c.1772, published 1796). In 1773-74, he was in Russia, where he had journeyed to thank Catherine II for buying his library. Despite her munificence, Diderot came rapidly to the conclusion that her despotic governance of the country would lead it to ruin (though he took care not to make his views known too overtly). In one of his last published writings, Aux Insurgents d’Amérique [To the American Insurgents] (1778), he praises the colonists who were in revolt against British oppression, and who were prepared to sacrifice their lives for freedom. He did not live to see their example inspire the revolution which swept away the old ecclesiastical and political order in France only a few years later.

As the role of genetics is better understood, it brings more closely into focus the very same moral problems with which Diderot grappled throughout his life. In this sense as in others, his preoccupation with the practical and political effects of materialism is becoming increasingly relevant; his prescient questioning of the novel form in Jacques foretells the post-modern preoccupation with the (im)possibility of telling the “truth” in fiction, and his mixing of fact and fiction offers direct parallels with the “faction” which is sometimes regarded as a modern literary innovation. All in all, Diderot is becoming recognised as perhaps the most far-sighted of the great Enlightenment writers, and his work is attracting increasing attention from many quarters. Yet much still remains to be investigated, and the extent of his genius is still to be fully measured.

Citation: Adams, David J.. "Denis Diderot". The Literary Encyclopedia. First published 01 May 2003 [, accessed 29 January 2022.]

1261 Denis Diderot 1 Historical context notes are intended to give basic and preliminary information on a topic. In some cases they will be expanded into longer entries as the Literary Encyclopedia evolves.

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