Rousseau was the eighteenth century's most famous citizen of Geneva, where he was born on 28 June 1712. His mother died in childbirth, and he was brought up by his father, until he was forced to flee Geneva to avoid imprisonment. The young Rousseau remained in Geneva with a poor relation for six years, and left the city when he was sixteen to travel Sardinia and France after his conversion to Catholicism.
In Savoy he enjoyed the patronage of Louise-Eléanore de la Tour du Pil, Baronne de Warens, who employed him as her steward and provided him with an education. They later became lovers. In 1742 Rousseau arrived in Paris, where he met Denis Diderot and was active among the philosophes and the Encyclopedists.
His first important work was Discours sur les sciences et les arts, which appeared in 1750. In it he argued the case for which he is perhaps best known: that progress and society, rather than improving humanity, in fact corrupt it. This insight, with its corrolary of essential human goodness which it is the business of society and education to nurture, provided the theme for many of his later works.
Rousseau worked with Diderot on the Encyclopédie, contributing articles on music. Early in his life, in fact, Rousseau himself wrote music, and his opera Devin du village (1752) earned him considerable prestige. He entered into a racorous debate promoting Italian opera buffa with its lively and expressive melodies over the richer harmony and formalism of French opera, targeting especially the works of the French composer Jean-Philippe Rameau.
In 1754 he converted back to Protestantism and returned to Geneva, bringing with him his mistress, Thérèse Levasseur. A second important philosophical work, the Discours sur l'origine de l'inegalité, appeared in 1755, and developed the themes of his first discourse by excoriating the institutions in society that create artificial inequalities between human beings, and therefore create vice among people who were good before they were exposed to society's corrupting influences. Individuals living alone, he argued, had no vices or disease; but they were forced to form societies to secure peace and possessions. They therefore banded together into families, and lived in a golden age. But as families developed into villages and developed the notion of property, jealousy arose, and promoted both inequality and vice. Rousseau praises Geneva for being the least subject to these vices of society. Du Contrat social (1762), with its famous opening, "Man was born free, but he is everywhere in chains," is an appeal for other states to adopt the republican principles of Geneva and thereby to escape the artificial inequalities imposed by other institutions.
In 1758 Rousseau retired to the country estate of Madame d'Épinay near Montmorency, and then to his own nearby cottage called Montlouis. Here he spent his most productive years. His most popular work, Julie; ou, la nouvelle Héloïse, appeared in 1761. The novel, inspired by the love affair of Abelard and Eloisa, explores the role of the sexes in domestic and public life.
In 1762, his Émile; ou, l'Éducation appeared, a treatise on the best education of the young. In it Rousseau describes how the tutor must work to protect the child from corrupting agencies; if he is shielded from malignant external influences, Rousseau argues, he will grow up without vice or even sickness. The outcry was considerable: the French Parlements ordered that the book should be burned and Rousseau arrested.
Rousseau escaped to Bern, Switzerland, but was later banished from the canton, and arrived in England. There he met David Hume, but their relationship was strained, and Rousseau returned to Paris incognito. For the next decade, he worked on a number of autobiographical writings: Confessions, Rousseau juge de Jean-Jacques (published posthumously in 1780), and Les Rêveries du promeneur solitaire (also published posthumously in 1782). He died on 2 July 1778.