The French thinker Marie Jean Antoine Nicolas Caritat, Marquis de Condorcet (1743-1794), expressed the spirit of the Enlightenment in reform proposals and writings on progress. He was the only philosophe to participate in the French Revolution.

Born in Ribemont in Picardy on Sept. 17, 1743, the Marquis de Condorcet was educated at the Jesuit college in Reims and later at the College of Navarre in Paris. He excelled in mathematics and in 1765 wrote the Essay on Integral Calculus. In 1769 he became a member of the Academy of Science, later becoming its perpetual secretary, and in 1782 was elected to the French Academy. He married Sophie de Grouchy in 1786, and their home became one of the famous salons of the period.

Prior to the French Revolution, Condorcet wrote biographies of A.R.J. Turgot and Voltaire and essays on the application of the theory of probabilities to popular voting, on the American...