Julien Offroy de La Mettrie

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Last Updated on May 6, 2015, by eNotes Editorial. Word Count: 2324

Article abstract: La Mettrie carried the Cartesian mechanism to its logical endpoint by positing, on the basis of his medical understanding, that a human being is a mechanism and that happiness arises from the effects of sense stimuli on this mechanism.

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Early Life

Julien Offroy de La Mettrie came from a comfortable background in Saint-Malo, a busy port town in northwestern France. His father was a merchant in the textile trade and a part of the bourgeoisie that made up the city’s informal governing class. There was enough money to educate the young La Mettrie very well. His early studies in the humanities were carried out in the collèges (private secondary schools) of Coutances and Caen; from there he went on to the Collège du Plessis in Paris. For a time he felt a religious calling and became interested in the Jansenist movement; little evidence of this phase remains, unless it be a later acceptance of a mechanistic causality of human thought and behavior reminiscent of the Jansenist conviction of predestination. In 1725, at the age of sixteen, he entered the Collège d’Harcourt, where Cartesianism was newly introduced, to study natural philosophy. He received his bachelor’s degree two years later. Thereafter he appears to have found his calling, and he entered the medical school at the University of Paris, shifting later to Reims, where he received his bachelor’s and doctorate in medicine in 1733.

La Mettrie went into medical practice in Reims and was never totally divorced from practice for the remainder of his short life. It must be emphasized that his knowledge of anatomy and medicine, gained at a time when both were advancing rapidly, underlay his philosophical views about the mechanism that is the human animal. New skills in dissection, and new medicines from the iatrochemists, became available month by month during this time, and it was easy to reach the exciting conclusion that the human animal-machine would be explicable within the lifetimes of scientists and physicians of the eighteenth century.

After qualification as a physician, La Mettrie moved to Leyden to further his studies with the Dutch chemist-physician Hermann Boerhaave. During his time there, he translated a number of Boerhaave’s texts on diseases, medicine and pharmaceuticals, and chemistry, and composed works of his own on treatment of vertigo and of venereal diseases, as well as reminiscences of his medical practice. La Mettrie married in 1739. He and his wife, the widow Marie-Louise Droneau, produced two children: a daughter in 1741, as well as a son in 1745 who did not survive childhood. The marriage also did not survive, and in 1742, La Mettrie removed to Paris, where he became personal physician to the duc de Grammont, and shortly thereafter the medical officer to the duc’s regiment in the Gardes Françaises. He took part in a number of engagements in the War of the Austrian Succession, which added to his medical skills and observations but left him permanently opposed to human bloodshed.

Life’s Work

During the eight years that remained to him, La Mettrie poured out a remarkable series of writings, most of which succeeded in getting him in trouble with some individual or group. In 1745, he published La Volupté (sensual delight), dedicated to the Marquise du Chatelet for her “personal contribution” to the subject matter of the book. In the same year, he produced his first major philosophical writing, Treatise on the Soul. This work was composed as the result of a serious illness and fever that overcame him during the last of the battles in which he was involved, the Siege of Freiburg. Observing the confusion of thought brought about by his physical state, he concluded that “thought is only the result of the organization of the machine [which is the human mind], and … the disruption of its authority greatly influences that part of ourselves that the metaphysicians call the soul.” From this observation it is a short step to the conclusion that human thought and behavior are produced by purely mechanical causes and that the soul, if it exists at all, very likely is as well. Of course, La Mettrie is not speaking from intellectual speculation but from medical experience. He had observed and performed dissections of the brain and nervous system and was familiar with the postmortem evidence that such-and-such a brain lesion was responsible for a particular delusion or disability in the patient before death. He could quite possibly have extended these observations in battlefield medicine, noting how head injuries affected the senses and physical abilities of the wounded. When he spoke of mechanical causes, he spoke with authority.

This did not sweeten the answers of his critics, however. They railed against the “pernicious statements spread through his book on the materialism and mortality of the soul, on the eternity of the world, and on Atheism.” La Mettrie was forced to give up his position with the Gardes Françaises, and his book was ordered burned by the public hangman in Paris. His medical competence was great enough that he moved on to a position as military hospital inspector for Lille, Ghent, Brussels, Antwerp, and Worms. However, he was not to be satisfied with one battle when he could produce two with a little extra effort. Disgusted by the self-serving incompetence of the medical establishment, particularly in France, in 1746 he produced Politique du médicine (the politics of medicine). The negative response was predictable, and with both clerics and physicians now opposed to him, La Mettrie found it wise to flee to Holland in the fall of 1746, not because any formal legal process faced him but because he feared the deviousness and caprice of the French judicial system.

He took up residence in Leyden, with its memories of student days and the time of apprenticeship to Boerhaave, but this calming effect did not last. Within a year, he produced an ironic comedy, La Faculté vengée (1747; the medical establishment revenged), continuing his attack on the physicians whom he regarded as charlatans. By the end of 1747, he published the work for which he is best remembered, Man a Machine (literally, “man, a mechanical device”).

In Man a Machine, he takes the last steps in the long trek from French philosopher René Descartes’s assertion, more than a century before, that animals are machines, and humans are machines also but possess souls that can relate them to God. La Mettrie draws on his extensive medical knowledge of the anatomy and physiology discovered in that intervening century: that muscular tissue is itself motile, for example, under electrical or other stimulus, thereby eliminating Cartesian mind-body duality with mind as sole causal agent; that disease of the body can cause disease of the mind, or soul; that extreme fatigue, hunger, or the effect of drugs can alter consciousness and even rational thought; that animals can be trained to do many of the things humans can do; that animals appear to possess emotions analogous to those of humans; and so on. His conclusion is that both animals and humans are mechanisms that think and feel and that no outside cause is necessary to account for this condition, nor is there any necessity to postulate a soul or an afterlife.

The ethics that follows from this formulation is that of natural law, a variation on the Golden Rule of not doing that which we would not want done to us. This is shared by animals, at least in the limited cases cited by La Mettrie. It further follows that because humans have only their sensations, perceptions, and mechanical causes to take into account, the object of people’s existence must be the happiness that proceeds from these sources. Such happiness, because it proceeds from mechanical or physiological causes only, may even take the form of actions that are considered monstrous by society at large. Individuals who find happiness in this way must be punished by society, but from a medical standpoint they should be treated with compassion. The theology of Man a Machine is dismissive. A supreme being might very probably exist, but this is a possibility of little everyday consequence. Such a being would not necessarily be worshiped, nor would it conduce to morality, any more than its absence would lead to immorality. It was clear that atheism—nonbelief—was the preferred belief.

This time the reaction to La Mettrie’s views was immediate and vicious. Thousands of pages of refutation and vilification appeared from Catholics and Protestants alike, even in normally liberal and tolerant Holland. The book had been published anonymously, so that the publisher Luzac was the only person who could be called to account. Called he was, before the Consistory of the Walloon Church of Leyden, and required to produce all copies of the book for destruction, to disclose the name of the author, and to apologize and promise never to make such an error of faith again. He conformed with the first and last of these demands but later produced and marketed a number of copies of Man a Machine to satisfy his own conviction that ideas must have free access. La Mettrie in the meantime had been identified as the author and found it necessary to flee Holland with his publisher’s help. He accepted an offer from Frederick II of Prussia to become “physician extraordinary” and lecteur to the king, as well as a member of the Royal Academy of Sciences of Prussia.

At Potsdam, he continued both his philosophical and his antimedical establishment writings, the latter in L’Ouvrage de Pénélope (1748; Penelope’s work), which enlarged on the earlier Politique du médicine with devastating satire on medical practice and particular physicians. In 1748, he also published Anti-Seneca: Or, The Sovereign Good, in which he enlarged on his views of happiness as a kind of health—that is, as the pleasurable well-being of the man-machine, available to all regardless of moral, social, or intellectual considerations. This earned for him an undeserved reputation as a voluptuary which—given his fondness for the table and for the ladies, as well as his fondness for scandalizing the disapproving—led to a distaste that spread far beyond the court at Potsdam. Other publications of his last years are Man a Plant, an extended analogy between the human or animal life and that of plants; Les Animaux plus que machines (1750; animals are more than machines), an attack by irony on animistic biology, with its postulated animal soul; Le Système d’Epicure (1750; The System of Epicurus, 1996), a confused examination of the origin of species; and two medical treatises of 1750, Traité sur la dyssenterie (treatise on dysentery) and Traité de l’asthme (treatise on asthma).

La Mettrie clearly enjoyed his life in court and his relation to the highly cultivated Frederick II (he of the flute concerti and the graceful prose style, who had nonetheless carved his empire out of former Habsburg territory), and his position in the Royal Academy of Sciences, presided over by Pierre-Louis Moreau de Maupertuis, who also hailed from Saint-Malo. Despite these personal pleasures, he longed to return to France and tried to enlist the aid of Voltaire, who was part of Frederick’s court for a time, to get influential friends to intercede for him.

Whether La Mettrie would have succeeded became moot when he died in the fall of 1751, a month short of his forty-second birthday. The circumstances of his death provided a field day for his detractors: At a dinner given by Lord Tyrconnel, France’s ambassador to Prussia, he consumed a large quantity of a pheasant-and-truffle pâté. It is conjectured that the pâté was spoiled or bacterially contaminated, for he fell ill and no treatment could prevent his death a few days later. Conventional critics saw in this a divine punishment for gluttony and a refutation of materialism, and a story even circulated that La Mettrie had repented and come back to the church on his deathbed. Frederick II, after ascertaining the facts, wrote a laudatory Éloge de La Mettrie (elegy for La Mettrie), which was read before the Royal Academy of Sciences and laid to rest this and other scurrilous allegations. La Mettrie’s body was buried in the French Catholic Church at Friedrichstadt.


La Mettrie’s thoroughgoing mechanism had some influence on his contemporaries, mainly a kind of cover that allowed them to develop their own anticlerical, sometimes atheistic views surreptitiously while someone else acted as the lightning rod. Among these were the encyclopedist Denis Diderot and his colleague Paul-Henri-Dietrich d’Holbach, as well as the later “Ideologue” and materialist Pierre-Jean-Georges Cabanis, who was born after La Mettrie’s untimely death. Materialism remained a thread of thought, or the foundation for thought, throughout the centuries following the eighteenth, but La Mettrie’s specific contributions fell from attention rather quickly. Whether this was because they were so explicitly based on scientific observations that were superseded in the great upsurge of medical and biological discovery of the nineteenth century, or simply because La Mettrie had gone as far as it was reasonably possible to go with mechanism as a philosophy, is impossible to say. He has since been recognized as a forerunner of current mechanism, particularly in the science of behaviorism, but without detailed connection of his ideas with those of today.

Additional Reading

Brehier, Emile. The History of Philosophy. Vol. 5 in The Eighteenth Century. Translated by Wade Baskin. Chicago: University of Chicago Press, 1967. Contains a short but sound discussion of the development of materialism in the middle of the eighteenth century.

Rosenfield, Leonora Cohen. From Beast-Machine to Man-Machine: Animal Soul in French Letters from Descartes to La Mettrie. 1940. Rev. ed. New York: Octagon Books, 1968. This older volume is indispensable for the understanding of the progression of mechanism.

Wellman, Kathleen Anne. La Mettrie: Medicine, Philosophy, and Enlightenment. Durham, N.C.: Duke University Press, 1992. Gives medical background of Julien Offroy de La Mettrie’s philosophical views.

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