La Mettrie Julien Offroy de (1707–51), French philosopher who was his generation’s most notorious materialist, atheist, and hedonist. Raised in Brittany, he was trained at Leiden by Hermann Boerhaave, an iatromechanist, whose works he translated into French. As a Lockean sensationalist who read Gassendi and followed the Swiss physiologist Haller, La Mettrie took nature to be life’s dynamic and ultimate principle. In 1745 he published Natural History of the Soul, which attacked Cartesian dualism and dispensed with God.
Drawing from Descartes’s animal-machine, his masterpiece, Man the Machine (1747), argued that the organization of matter alone explains man’s physical and intellectual faculties. Assimilating psychology to mechanistic physiology, La Mettrie integrated man into nature and proposed a materialistic monism. An Epicurean and a libertine, he denied any religious or rational morality in Anti-Seneca (1748) and instead accommodated human behavior to natural laws. Anticipating Sade’s nihilism, his Art of Enjoying Pleasures and Metaphysical Venus (1751) eulogized physical passions. Helvétius, d’Holbach, Marx, Plekhanov, and Lenin all acknowledged a debt to his belief that ‘to write as a philosopher is to teach materialism.’ J.-L.S.