Dans Du contrat social, Rousseau établit qu'une organisation sociale « juste » repose sur un pacte garantissant l'égalité et la liberté entre tous les citoyens. Ce pacte est contracté entre tous les participants, c'est-à-dire l'ensemble exhaustif des citoyens. Dans le pacte social, chacun renonce à sa liberté naturelle pour gagner une liberté civile. La souveraineté populaire est le principe fondamental du contrat social. L'indivisibilité de cette souveraineté est un autre principe fondamental, par lequel il faut comprendre que le pouvoir du Souverain ne saurait être divisé (Rousseau emploie ce terme pour désigner le peuple souverain) et il ne peut s'en séparer par intérêt particulier, car l'intérêt particulier est contraire à la recherche de l'intérêt général, seul objectif du contrat social. Ce contrat social, Rousseau le voit comme faisant suite à l'état de nature dans lequel règne le droit du plus fort.

Jean-Jacques Rousseau (28 June 1712 - 2 July 1778) was a Genevan philosopher, writer and composer. His political philosophy influenced the progress of the Enlightenment throughout Europe, as well as aspects of the French Revolution and the development of modern political, economic and educational thought.
His Discourse on Inequality and The Social Contract are cornerstones in modern political and social thought. Rousseau's sentimental novel Julie, or the New Heloise (1761) was important to the development of preromanticism and romanticism in fiction. His Emile, or On Education (1762) is an educational treatise on the place of the individual in society. Rousseau's autobiographical writings-the posthumously published Confessions (composed in 1769), which initiated the modern autobiography, and the unfinished Reveries of a Solitary Walker (composed 1776-1778)-exemplified the late-18th-century Age of Sensibility, and featured an increased focus on subjectivity and introspection that later characterized modern writing.
Rousseau befriended fellow philosophy writer Denis Diderot in 1742, and would later write about Diderot's romantic troubles in his Confessions. During the period of the French Revolution, Rousseau was the most popular of the philosophers among members of the Jacobin Club. He was interred as a national hero in the Panthéon in Paris, in 1794, 16 years after his death.