A fever convinced an 18th-century doctor that thought is made of flesh
While ill with a fever, the French physician Julien Offray de La Mettrie noticed his thinking change as his blood raced. He concluded the mind is simply the brain and nerves at work, argued it in Man a Machine in 1747, and was driven from France and then from the Netherlands.
Born in Saint-Malo in 1709, the son of a prosperous textile merchant, La Mettrie first leaned towards the priesthood before switching to philosophy, natural science and then medicine. He trained in Paris and in Leiden under the celebrated Herman Boerhaave, whose ideas he later spread by translation. Serving as surgeon to the French Guards during the War of the Austrian Succession left him with a lasting loathing of violence.
His first book, the Natural History of the Soul of 1745, caused such uproar that he lost his post and fled to Leiden. There he wrote Man a Machine, pushing the case further: humans are complex animals without souls, differing from apes only in how intricately their matter is arranged. He likened the gap to that between a fine pendulum clock by Huygens and an ordinary watch, and suggested a trained ape might learn language. Some of his evidence, such as a headless chicken still running, was crude, and his writing was more provocative than scientific.
He built on Descartes' picture of the body as mechanism but rejected Descartes' split between body and mind, even insisting Descartes was secretly a materialist. The philosopher David Skrbina argues he was no cold mechanist, reading him as a vitalistic materialist who thought matter itself could feel. In Berlin, where Frederick the Great made him court reader in 1748, he wrote the Discourse on Happiness, arguing that guilt instilled in childhood does lasting harm and that pleasure should guide life. Voltaire, Diderot and d'Holbach were appalled, and his reputation stayed buried until Friedrich Albert Lange revived it a century later.
His influence runs through the physician Pierre Cabanis to behaviourism, cybernetics and the philosophy of artificial intelligence, even if many behaviourists never read him. His end fitted his reputation: at a feast held by the grateful French ambassador, he reportedly gorged on truffled pheasant pâté, fell ill with fever and died in November 1751.
Source: Julien Offray de La Mettrie
