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Thinkers

Denis Diderot

Enlightenment · Europe · 1713 to 1784

French writer who led the making of the Encyclopedia, a great work that gathered knowledge and spread reason and science.

What it is

Denis Diderot (1713 to 1784) was a French philosopher, writer and art critic, and the co-founder and chief editor of the Encyclopédie. He was born in Langres, the son of a cutler, studied under the Jesuits and moved to Paris as a young man, where he struggled for years to make a living as a writer. After Voltaire he is the best-known leader of the philosophes, the circle around which the Enlightenment gathered after 1750.

With Jean le Rond d'Alembert he set out in the Encyclopédie to "change the common way of thinking". It began in 1745 as a translation of an English dictionary and grew into a vast original work, to which Diderot himself contributed nearly six thousand articles. In later life he was helped by Catherine the Great of Russia, whose court he visited in 1773.

The main ideas

  • Knowledge as a shared work. The Encyclopédie was a new model of knowledge: collaborative, comprehensive and meant for ordinary readers, to change how people think.
  • Changing the common way of thinking. The aim was not only to collect facts but to change habits of thought.
  • Between belief and doubt. His early writings, the Pensées philosophiques and the Promenade du sceptique, play with deism, scepticism and natural religion.
  • An editor as a thinker. Alongside his writing he spent fifteen years editing, and he saw the editor's work as part of the philosophical project.
  • Art and criticism. He was also an art critic, and the Enlightenment he helped to lead took the arts as seriously as the sciences.

What it looks like in practice

Imagine setting out to write down everything a community knows, from how a craftsperson makes a tool to what a philosopher believes, and to put it in one reference work anyone can read. Diderot would say that the act of collecting and organising is itself a way of changing what people take for granted. This is an illustration of his line of questioning, not a passage from his writing.

Books and moments

  • The Encyclopédie, with d'Alembert, was begun in 1745 and its text volumes were completed in 1765.
  • Pensées philosophiques (1746, expanded in 1762) is one of his first philosophical works.
  • Promenade du sceptique (1747) is another early work, about scepticism and religion.

Questions and criticism

  • Shifting views. His early writings play with deism and scepticism, and it is hard to say when and how far his own beliefs moved.
  • A hard start. He came from an artisan family, struggled for years in Paris and was released from prison in 1749, as the Encyclopédie was taking shape.
  • Can a reference work change minds? It is fair to ask whether gathering knowledge in one place does more than record the beliefs of its editors.

Close neighbours

Voltaire is the figure beside whom he is usually placed as a leader of the philosophes. The pages on Jean-Jacques Rousseau and David Hume show two other thinkers of his age.

Written by epchē in our own words, and checked against independent sources on 29 October 2026. The sources are listed below.

Who they connect to

Influenced

  • Baron d'Holbach · The two were close friends and shared a materialist view. (scholars disagree about this link)

Influenced by

  • Francis Bacon · The plan of the Encyclopedia names Bacon as the model for organising all knowledge.

Other Enlightenment thinkers

Sources we used

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