Julien Offray de La Mettrie

Julien Offray de La Mettrie (Saint-Malo, 1709 – Potsdam, 1751) was a French physician and philosopher, and one of the earliest materialists of the Enlightenment. He is remembered above all for arguing that human beings are complex animals with no more soul than any other animal, and that the mind is part of the body. His thought stands between the legacy of Descartes, whom he read in a materialist key, and Epicureanism, which he drew on throughout his work.

The son of a prosperous textile merchant, he was schooled in Coutances and Caen before attending the Collège du Plessis in Paris. After a few years of theology in Jansenist schools he turned to medicine and qualified in Reims before the age of twenty. In 1733 he went to Leiden to study under Boerhaave, whose naturalist and Spinozist ideas left a lasting mark on him. Back in Paris in 1742, he became a military surgeon, an experience that left him with a lasting aversion to violence.

During a bout of fever he observed in himself how a faster circulation of the blood affected his thinking, and concluded that mental processes are the effects of organic changes in the brain and nervous system. He set this out in the Natural History of the Soul (1745), a book that caused such uproar that he had to seek refuge in Leiden. There he wrote Man a Machine and Man a Plant, consistently materialist treatises. His ethics appear in the Discourse on Happiness and The Art of Enjoying, where he holds that the pleasures of the senses are the end of life and that virtue can be reduced to self-love. He also argued that atheism was the only way to end the quarrels of theologians.

In the late 1740s he settled in Berlin, where Frederick the Great allowed him to practise medicine and made him a reader to the court. There he published the Discourse on Happiness, which set him against Voltaire, Diderot and D'Holbach. He died in Potsdam in 1751, aged 41, after a severe indigestion that is said to have followed a pheasant pâté with truffles. Frederick gave his funeral oration, which remains an important source on his life, though he described him as a good physician and a very poor author.

His influence was greater in medicine and psychology than in academic philosophy. Pierre Jean Georges Cabanis, a prominent French physician, built on his materialism but moderated it. His reductionist approach echoes in behaviourism and, more distantly, in cognitive science and artificial intelligence. For a long time, however, the hostility he provoked meant he was rarely cited.