18 Key Thinkers of the Enlightenment

Reading Voltaire's tragedy L'Orphelin de la Chine at Madame Geoffrin's salon, painted in 1812 by Gabriel Lemonnier (1743-1824), oil on canvas, 129,5 x196
Reading Voltaire's tragedy L'Orphelin de la Chine at Madame Geoffrin's salon, painted in 1812 by Gabriel Lemonnier (1743-1824). DEA / G. DAGLI ORTI / Getty Images

At the most visible end of the Enlightenment were a group of thinkers who consciously sought human advancement through logic, reason, and criticism. Biographical sketches of these key figures are below in alphabetical order of their surnames.

Alembert, Jean Le Rond d’ 1717 – 1783

Jean le Rond d'Alembert
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The illegitimate son of hostess Mme de Tencin, Alembert was named after the church on whose steps he was abandoned. His supposed father paid for an education and Alembert became famous both as a mathematician and as co-editor of the Encyclopédie, for which he authored over a thousand articles. Criticism of this – he was accused of being too anti-religious – saw him resign and devote his time to other works, including literature. He turned down employment from both Frederick II of Prussia and Catherine II of Russia.

Beccaria, Cesare 1738 - 1794

Portrait of Cesare Marquis Beccaria Bonesana
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The Italian author of On Crimes and Punishments, published in 1764, Beccaria argued for punishment to be secular, rather than based on religious judgments of sin, and for legal reforms including the end of capital punishment and judicial torture. His works proved to be hugely influential among European thinkers, not just those of the Enlightenment.

Buffon, Georges-Louis Leclerc 1707 – 1788

Portrait of Georges-Louis Leclerc Comte de Buffon
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The son of a highly ranked legal family, Buffon changed from a legal education to science and contributed to the Enlightenment with works on natural history, in which he rejected the biblical chronology of the past in ​favor of the Earth being older and flirted with the idea that species could change. His Histoire Naturelle aimed to classify the whole natural world, including humans.

Condorcet, Jean-Antoine-Nicolas Caritat 1743 – 1794

Marie Jean Antoine Nicolas Caritat, Marquis de Condorcet (1743 1794) engraving from the book 'Album of science famous scientist discoveries' in 1899; (His ashes with those of Monge and the Abbe Gregoire will be transferred to Pantheon December 12 1993.)
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One of the leading thinkers of the late Enlightenment, Condorcet focused largely on science and mathematics, producing important works on probability and writing for the Encyclopédie. He worked in the French government and became a deputy of the Convention in 1792, where he promoted education and freedom for slaves, but died during the Terror. A work on his belief in human progress was published posthumously.

Diderot, Denis 1713 – 1784

Denis Diderot
By Louis-Michel van Loo - Flickr, Public Domain, Link

Originally the son of artisans, Diderot first entered the church before leaving and working as a law clerk. He achieved fame in the Enlightenment era chiefly for editing arguably the key text, his Encyclopédie, which took up over twenty years of his life. However, he wrote widely on science, philosophy and the arts, as well as plays and fiction, but left many of his works unpublished, partly a result of being imprisoned for his early writings. Consequently, Diderot only gained his reputation as one of the titans of the Enlightenment after his death, when his work was published.

Gibbon, Edward 1737 – 1794

Edward Gibbon
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Gibbon is the author of the most famous work of history in the English language, The History of the Decline and Fall of the Roman Empire. It has been described as a work of “humane skepticism”, and marked Gibbon out as the greatest of the Enlightenment historians. He was also a member of the British parliament.

Herder, Johann Gottfried von 1744 – 1803

Johann Gottfried von Herder (1744 - 1803)
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Herder studied at Königsburg under Kant and also met Diderot and d’Alembert in Paris. Ordained in 1767, Herder met Goethe, who obtained for him the position of a court preacher. Herder wrote on German literature, arguing for its independence, and his literary criticism became a heavy influence on later Romantic thinkers.

Holbach, Paul-Henri Thiry 1723 – 1789

Paul Henri D'Holbach
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A successful financier, Holbach’s salon became a meeting place for Enlightenment figures like Diderot, d’Alembert, and Rousseau. He wrote for the Encyclopédie, while his personal writings attacked organized religion, finding their most famous expression in the co-written Systéme de la Nature, which brought him into conflict with Voltaire.

Hume, David 1711 – 1776

David Hume Statue
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Building his career after a nervous breakdown, Hume gained attention for his History of England and established a name for himself among Enlightenment thinkers while working at the British embassy in Paris. His ​best-known work is the full three volumes of the Treatise of Human Nature but, despite being friends with people like Diderot, the work was largely ignored by his contemporaries and only gained a posthumous reputation.

Kant, Immanuel 1724 – 1804

Emmanuel Kant. Portrait of Immanuel Kant 1724-1804, German philosopher. Engraving
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A Prussian who studied at the University of Königsburg, Kant became a professor of mathematics and philosophy and later rector there. The Critique of Pure Reason, arguably his most famous work, is just one of several key Enlightenment texts which also include his era-defining essay What is Enlightenment?

Locke, John 1632 – 1704

John Locke,English philosopher.
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A key thinker of the early Enlightenment, the English Locke was educated at Oxford but read wider than his course, gaining a degree in medicine before pursuing a varied career. His Essay Concerning Human Understanding of 1690 challenged Descartes’ views and influenced later thinkers, and he helped pioneer views on toleration and produced views on government which would underpin later thinkers. Locke was forced to flee England for Holland in 1683 because of his links to plots against the king, before returning after William and Mary took the throne.

Montesquieu, Charles-Louis Secondat 1689 – 1755

Charles-Louis de Secondat
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Born into a prominent legal family, Montesquieu was a lawyer and president of the Bordeaux Parlement. He first came to the attention of the Parisian literary world with his satire Persian Letters, which tackled French institutions and the “Orient”, but is best known for Esprit des Lois, or The Spirit of the Laws. Published in 1748, this was an examination of different forms of government which became one of the most widely disseminated works of the Enlightenment, especially after the church added it to their banned list in 1751.

Newton, Isaac 1642 – 1727

Painting of Sir Isaac Newton
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Although involved in alchemy and theology, it is Newton’s scientific and mathematical achievements for which he is chiefly recognized. The methodology and ideas he set forth in key works like the Principia helped forge a new model for “natural philosophy” which the thinkers of the Enlightenment tried to apply to humanity and society.

Quesnay, François 1694 – 1774

Quesnay, François
See page for author [Public domain], via Wikimedia Commons

A surgeon who eventually ended up working for the French king, Quesnay contributed articles for the ​Encyclopédie and hosted meetings at his chambers among Diderot and others. His economic works were influential, developing a theory called Physiocracy, which held that land was the source of wealth, a situation requiring a strong monarchy to secure a free market.

Raynal, Guillaume-Thomas 1713 - 1796

A philosopher is writing the words Auri Sacra Fames (Hunger for Gold) on a column, while Indians are massacred and enslaved in the background.
A philosopher is writing the words Auri Sacra Fames (Hunger for Gold) on a column, while Indians are massacred and enslaved in the background. Illustration by Marillier, draftsman for William Thomas Raynal, History of the East and West Indies, Volume 2, 1775. By Marillier, dessinateur, Guillaume ; Thomas Raynal, auteur du texte (BnF-Gallica -(FR-BnF 38456046z)) [Public domain], via Wikimedia Commons

Originally a priest and personal tutor, Raynal emerged onto the intellectual scene when he published Anecdotes Littéaires in 1750. He came into contact with Diderot and wrote his most famous work, Histoire des deux Indes (History of the East and West Indies), a history of the colonialism of European nations. It has been called a “mouthpiece” of Enlightenment ideas and thought, although the most groundbreaking passages were written by Diderot. It proved so popular across Europe that Raynal left Paris to avoid the publicity, later being temporarily exiled from France.

Rousseau, Jean-Jacques 1712 – 1778

Jean-Jacques Rousseau, portrait. Swiss-French philosopher, writer, and composer
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Born in Geneva, Rousseau spent the early years of his adult life traveling in poverty, before educating himself and traveling to Paris. Increasingly turning from music to writing, Rousseau formed an association with Diderot and wrote for the ​​Encyclopédie, before winning a prestigious award which pushed him firmly onto the Enlightenment scene. However, he fell out with Diderot and Voltaire and turned away from them in later works. On one occasion Rousseau managed to alienate the major religions, forcing him to flee France. His Du Contrat Social became a major influence during the French Revolution and he has been called a major influence on Romanticism.

Turgot, Anne-Robert-Jacques 1727 – 1781

By Credited as "Drawn by Panilli, engraved by Marsilly" [Public domain], via Wikimedia Commons

Turgot was something of a rarity among leading figures in the Enlightenment, for he held high office in​ the French government. After beginning his career in the Paris Parlement he became Intendant of Limoges, Navy Minister, and Finance Minister. He contributed articles to the Encyclopédie, chiefly on economics, and wrote further works on the subject, but found his position in government weakened by a commitment to free trade in wheat which led to high prices and riots.

Voltaire, François-Marie Arouet 1694 – 1778

Voltaire, portrait
By Nicolas de Largillière - Scan by User:Manfred Heyde, Public domain, Collegamento

Voltaire is one of, if not the, most dominant Enlightenment figures, and his death is sometimes cited as the end of the period. The son of a lawyer and educated by Jesuits, Voltaire wrote widely and frequently on many subjects for a long time period, also maintaining correspondence. He was imprisoned early in his career for his satires and spend time exiled in England before a brief period as court historiographer to the French king. After this, he continued to travel, finally settling on the Swiss border. He is perhaps best known today for his satire Candide.