The French philosopher and educator Étienne Bonnot de Condillac (1715-1780) was a Lockean psychologist and early positivist who greatly influenced economic and political thought in prerevolutionary France.

On Sept. 30, 1715, Étienne Bonnot was born to Gabriel Bonnot, Vicomte de Mably. He later became the Abbé de Condillac, a territory purchased by his father in 1720. Educated in Paris at the Sorbonne and at St-Suplice, he was ordained a priest in 1740 but chose to become a writer and a tutor. From 1740 to 1758 he frequented the literary salons of Paris and worked at his own education. John Locke's psychology and empiricism and Sir Isaac Newton's search for fundamental principles were strong influences in his reading.

Condillac's Essai sur l'origine des connaissances humaines (1746) followed Locke's principles but reduced the operations of human understanding to one principle--sensation--and treated reflection as a sequence and comparison of sensations. The work stated language to...