Divergences among the early thinkers of the Enlightenment show that, while they shared many of the same premises and questions, the answers they found differed widely. The spread of this spirit of inquiry and debate owed a great deal to the work of the philosophes (fee-luh-ZAWFZ), a group of intellectuals who proudly proclaimed that they, at long last, were bringing the light of reason to their ignorant fellow humans. Philosophe is the French word for “philosopher,” and in the mid-eighteenth century France became a hub of Enlightenment thought. There were at least three reasons for this. First, French was the international language of the educated classes, and France was the wealthiest and most populous country in Europe. Second, the rising unpopularity of King Louis XV and his mistresses generated growing discontent and calls for reform among the educated elite. Third, the French philosophes made it their goal to reach a larger audience of elites, many of whom were joined together in a concept inherited from the Renaissance known as the Republic of Letters — an imaginary transnational realm of the well educated.

One of the greatest philosophes, the baron de Montesquieu (mahn-tuhs-KYOO) (1689–1755), brilliantly pioneered this approach in The Persian Letters, an extremely influential social satire published in 1721 and considered the first major work of the French Enlightenment. It consisted of amusing letters supposedly written by two Persian travelers who as outsiders saw European customs in unique ways, thereby allowing Montesquieu a vantage point for criticizing existing practices and beliefs.

Having gained fame by using wit as a weapon against cruelty and superstition, Montesquieu turned to the study of history and politics. His interest was partly personal, for, like many members of the French robe nobility, he was disturbed by the growth in absolutism under Louis XIV (see “Louis XIV and Absolutism” in Chapter 15). But Montesquieu was also inspired by the example of the physical sciences, and he set out to apply the critical method to the problem of government in The Spirit of Laws (1748). The result was a complex, comparative study of republics, monarchies, and despotisms.

Showing that forms of government were shaped by history and geography, Montesquieu focused on the conditions that would promote liberty and prevent tyranny. He argued for a separation of powers, with political power divided and shared by a variety of classes and legal estates. Admiring greatly the English balance of power, Montesquieu believed that in France the thirteen high courts — the parlements — were frontline defenders of liberty against royal despotism. Apprehensive about the uneducated poor, Montesquieu was clearly no democrat, but his theory of separation of powers had a great impact on the constitutions of the young United States in 1789 and of France in 1791.

The most famous and perhaps most representative philosophe was François Marie Arouet, who was known by the pen name Voltaire (vohl-TAIR) (1694–1778). In his long career, this son of a comfortable middle-class family wrote more than seventy witty volumes, hobnobbed with royalty, and died a millionaire through shrewd speculations. His early career, however, was turbulent, and he was arrested on two occasions for insulting noblemen. Voltaire moved to England for three years in order to avoid a longer prison term in France, and there he came to share Montesquieu’s enthusiasm for English liberties and institutions.

Returning to France, Voltaire had the great fortune of meeting Gabrielle-Emilie Le Tonnelier de Breteuil, marquise du Châtelet (SHAH-tuh-lay) (1706–1749), a noblewoman with a passion for science. Inviting Voltaire to live in her country house at Cirey in Lorraine and becoming his long-time companion (under the eyes of her tolerant husband), Madame du Châtelet studied physics and mathematics and published scientific articles and translations, including the first — and only — translation of Newton’s Principia into French. (See “Primary Source 16.3: Du Châtelet, Foundations of Physics.”) Excluded from the Royal Academy of Sciences because she was a woman, Madame du Châtelet had no doubt that women’s limited role in science was due to their unequal education. Discussing what she would do if she were a ruler, she wrote, “I would reform an abuse which cuts off, so to speak, half the human race. I would make women participate in all the rights of humankind, and above all in those of the intellect.”7

While living at Cirey, Voltaire wrote works praising England and popularizing English science. He had witnessed Newton’s burial at Westminster Abbey in 1727, and he lauded Newton as history’s greatest man, for he had used his genius for the benefit of humanity. In the true style of the Enlightenment, Voltaire mixed the glorification of science and reason with an appeal for better individuals and institutions.

Yet, like almost all of the philosophes, Voltaire was a reformer, not a revolutionary, in politics. He pessimistically concluded that the best one could hope for in the way of government was a good monarch, since human beings “are very rarely worthy to govern themselves.” He lavishly praised Louis XIV and conducted an enthusiastic correspondence with King Frederick the Great of Prussia, whom he admired as an enlightened monarch (see page 530). Nor did Voltaire believe in social and economic equality, insisting that the idea of making servants equal to their masters was “absurd and impossible.” The only realizable equality, Voltaire thought, was that “by which the citizen only depends on the laws which protect the freedom of the feeble against the ambitions of the strong.”8

Voltaire’s philosophical and religious positions were much more radical than his social and political beliefs. In the tradition of Bayle, his writings challenged the Catholic Church and Christian theology at almost every point. Voltaire clearly believed in God, but, like many eighteenth-century Enlightenment thinkers, he was a deist, envisioning God as akin to a clockmaker who set the universe in motion and then ceased to intervene in human affairs. Above all, Voltaire and most of the philosophes hated all forms of religious intolerance, which they believed led to fanaticism. Simple piety and human kindness — as embodied in Christ’s commandments to “love God and your neighbor as yourself” — were religion enough.

The ultimate strength of the philosophes lay in their dedication and organization. The philosophes felt keenly that they were engaged in a common undertaking that transcended individuals. Their greatest and most representative intellectual achievement was, quite fittingly, a group effort — the seventeen-volume Encyclopedia: The Rational Dictionary of the Sciences, the Arts, and the Crafts, edited by Denis Diderot (DEE-duh-roh) (1713–1784) and Jean le Rond d’Alembert (dah-luhm-BEHR) (1717–1783). From different circles and with different interests, the two men set out to find coauthors who would examine the rapidly expanding whole of human knowledge. Even more fundamentally, they set out to teach people how to think critically and objectively about all matters. As Diderot said, he wanted the Encyclopedia to “change the general way of thinking.”9

The Encyclopedia survived initial resistance from the French government and the Catholic Church. Published between 1751 and 1772, it contained seventy-two thousand articles by leading scientists, writers, skilled workers, and progressive priests, and it treated every aspect of life and knowledge. Not every article was daring or original, but the overall effect was little short of revolutionary. Science and the industrial arts were exalted, religion and immortality questioned. Intolerance, legal injustice, and out-of-date social institutions were openly criticized. The encyclopedists were convinced that greater knowledge would result in greater human happiness, for knowledge was useful and made possible economic, social, and political progress. Summing up the new worldview of the Enlightenment, the Encyclopedia was widely read, especially in less-expensive reprint editions, and it was extremely influential.