1) His Biography
Julien Offray de La Mettrie was born on December 25, 1709, in Saint-Malo, a port city in Brittany, France. He belonged to a bourgeois family, and his father was a prosperous merchant. La Mettrie’s early education was steeped in the scholastic tradition, though he soon developed a sceptical attitude towards traditional forms of knowledge. Initially trained for the clergy, he shifted his focus to the sciences, particularly medicine, which would later serve as a foundation for his radical philosophical assertions. His interest in the human body and its functions would become central to his later materialist philosophy.
He pursued medical studies in Paris and later in Leiden under the celebrated Dutch physician Hermann Boerhaave, who was one of the most influential figures in European medicine during the eighteenth century. Under Boerhaave’s mentorship, La Mettrie acquired a scientific approach rooted in empirical observation and experimentation. His exposure to Enlightenment rationalism and progressive medical thinking during this time planted the seeds of his future philosophical radicalism. He became particularly interested in the physiological functions of the human body and began to contemplate the extent to which mental processes could be explained in purely physical terms.
Upon returning to France, La Mettrie worked as a military physician during the War of the Austrian Succession. It was during this time that he began publishing his medical observations and reflections, which quickly gained both notoriety and condemnation. His medical work Histoire naturelle de l’âme (Natural History of the Soul) in 1745 was one of his first philosophical texts, where he hinted at a materialist view of human consciousness. The backlash from this publication marked the beginning of his controversial public life. It provoked outrage from the French authorities and clergy, leading him to flee France and seek refuge in the Netherlands.
His most infamous and revolutionary work, L’Homme Machine (Man a Machine), was published in 1747 in Leiden. In this text, La Mettrie took a radical position by asserting that humans are entirely physical beings—machines governed by mechanical laws. This work incited intense hostility from religious and political institutions, and even the relatively tolerant Netherlands became unsafe for him. He was forced to flee again, this time to Prussia, where he was welcomed by Frederick the Great, who admired La Mettrie’s intellect and wit, even if he did not wholly agree with his ideas.
In Berlin, La Mettrie found temporary stability. Frederick II appointed him to the post of court physician and even encouraged his continued writing. While in Prussia, La Mettrie published several more works, including L’Homme Plante (Man a Plant) and Discours sur le bonheur (Discourse on Happiness). These texts further developed his naturalist and hedonist philosophy, emphasising the physical basis of human life and the pursuit of pleasure as a rational end. Although he enjoyed the relative freedom afforded by Frederick’s court, his works remained deeply controversial, and he was often viewed with suspicion by both conservatives and moderate Enlightenment thinkers.
La Mettrie’s lifestyle in Berlin was marked by contradiction—while he advocated for the rational pursuit of pleasure, he was known for his extravagance and disregard for social decorum. His final years were spent writing and debating with other intellectuals in the Prussian court. His health, however, declined rapidly, and in 1751, he died at the age of 41 after suffering from a severe fever. Ironically, some accounts claim that his death was hastened by overindulgence at a banquet, which to some served as a grim reinforcement of his hedonist principles.
Julien Offray de La Mettrie remains a controversial figure in the history of philosophy. His commitment to a radical form of materialism set him apart from many of his contemporaries, even within the Enlightenment. He challenged deeply rooted dualisms between body and soul, science and religion, and reason and passion. Though ostracised during his lifetime and largely dismissed for generations afterward, La Mettrie’s writings have seen a revival in recent years, particularly among scholars interested in the intersections of philosophy, biology, and consciousness. His work stands as a testament to the audacity and dangers of radical thinking in an era still dominated by religious and moral orthodoxy.
2) Main Works
L’Homme Machine (Man a Machine) – 1747:
Arguably La Mettrie’s most famous and incendiary work, L’Homme Machine articulates his core thesis that human beings are nothing more than complex machines. In this text, La Mettrie denies the existence of an immaterial soul, arguing instead that all mental phenomena—thoughts, desires, sensations—are the result of physical processes in the body. Drawing from his medical background, he likens the brain to a finely tuned organ whose functions can be studied and explained like any other part of the body. This was a direct challenge to Cartesian dualism, which posited a fundamental separation between mind and body.
The book caused immediate outrage, as it appeared to strip humans of spiritual significance and reduce them to automata. La Mettrie’s vision of the human being as wholly corporeal and determined by physical laws placed him at odds with both the Church and many Enlightenment philosophers who still maintained some notion of soul or rational essence. His fearless materialism and bold analogies between humans and animals incited accusations of atheism and immorality. Nonetheless, L’Homme Machine is now recognised as a groundbreaking work in the history of philosophy and early neuroscience, foreshadowing debates that continue to this day regarding the nature of consciousness and the mind-body problem.
L’Homme Plante (Man a Plant) – 1748:
In L’Homme Plante, La Mettrie further develops his naturalistic philosophy by drawing an extended analogy between the human being and a plant. The work underscores the idea that life, in all its forms, follows the same basic principles of growth, nourishment, and response to stimuli. Just as a plant requires specific physical conditions to thrive, so too does the human organism. He contends that humans and plants are both governed by the same laws of nature, differing only in complexity. This metaphor serves not only as a critique of spiritual explanations of life but also as a celebration of life’s material continuity.
This work reinforces La Mettrie’s conviction that there is no fundamental divide between different forms of life, thereby subverting long-standing hierarchical conceptions of nature with humans at the pinnacle. By comparing man to a plant, he simultaneously naturalises and relativises human exceptionalism. Though less well-known than L’Homme Machine, this work is significant for its poetic approach to materialism and its implications for the study of biology and ethics. It invites the reader to reconsider human identity not as metaphysically distinct, but as a flourishing, natural phenomenon embedded in the organic world.
Discours sur le bonheur (Discourse on Happiness) – 1748:
In Discours sur le bonheur, La Mettrie explores the ethical dimensions of his materialist worldview, proposing that the pursuit of happiness is both natural and rational. He rejects religious and metaphysical justifications for morality and instead advocates for hedonism grounded in human nature. Happiness, according to La Mettrie, arises from the healthy functioning of the body and the pleasures that life can offer. He stresses that virtue and vice are not dictated by divine command but are relative to individual temperament and circumstance.
This work is notable for its unapologetic embrace of pleasure as the highest good. La Mettrie defends the idea that seeking joy, bodily well-being, and emotional satisfaction is not only legitimate but essential for a fulfilling life. His philosophy of happiness challenges the asceticism of traditional religious moralities and the abstract universalism of Kantian ethics. Instead, he offers a vision of human flourishing rooted in biology and individuality. Although this hedonistic stance earned him severe criticism, it anticipates modern discussions in psychological ethics and secular approaches to well-being.
Système d’Épicure (The System of Epicurus) – 1750:
In this posthumously published work, La Mettrie aligns himself explicitly with the ancient philosopher Epicurus, whom he admired for his materialism and ethics of pleasure. The Système d’Épicure presents a synthesis of Epicurean physics and ethics adapted to Enlightenment sensibilities. La Mettrie embraces atomism and the rejection of divine providence, presenting a universe governed by chance and necessity rather than purpose or divine design. He also echoes Epicurus in his ethical framework, advocating a life of measured pleasures and the avoidance of pain.
What distinguishes La Mettrie’s interpretation is his emphasis on empirical science and medicine as the basis for understanding both the world and human well-being. He modernises Epicureanism by drawing on contemporary discoveries and reframing ancient ideas through a medical and mechanistic lens. This work serves as both a homage and a critical update of Epicurean thought, showcasing La Mettrie’s effort to build a cohesive philosophical system in opposition to religious dogma and Cartesian rationalism. It remains a crucial text for understanding the lineage of materialist ethics from antiquity to the modern age.
Histoire naturelle de l’âme (Natural History of the Soul) – 1745:
This early work marks La Mettrie’s first major step into philosophical controversy. In Histoire naturelle de l’âme, he challenges the notion of the soul as an immaterial, immortal entity by examining it through the lens of empirical science. He proposes that mental activities arise from physiological processes in the brain, arguing that the soul is a function of matter, not an independent substance. Drawing from clinical observations and neurological studies, he contends that disruptions in brain activity can affect thought and behaviour, thereby undercutting spiritualist explanations.
The reception of this work was extremely hostile; it was publicly condemned and even burned in some places. Nevertheless, it laid the intellectual groundwork for L’Homme Machine and foreshadowed future debates in psychology and neuroscience. La Mettrie’s insistence on studying the soul scientifically was not merely provocative but pioneering. It positioned him as a forebear of biological psychology and cognitive science, well ahead of his time. The Histoire naturelle de l’âme remains a crucial document in the history of naturalistic approaches to human consciousness.
3) Main Themes
Materialism and the Denial of the Soul:
One of the most defining features of La Mettrie’s thought is his radical materialism, which held that all phenomena—including mental and spiritual experiences—are grounded in physical processes. He rejected the Cartesian dualism that separated mind and body, instead insisting that the soul was not a distinct substance but rather a function of the body’s organisation, particularly the brain. This theme is most famously advanced in L’Homme Machine, where he argues that thought is a product of organic matter, thereby flattening the hierarchy between body and mind that had dominated Western thought for centuries.
La Mettrie’s materialism rested on three critical premises. First, he believed that empirical evidence from medicine and physiology demonstrated the dependence of mental states on the physical condition of the body. Second, he asserted that humans and animals share the same mechanistic basis of thought and action, which radically undercut religious and philosophical anthropocentrism. Third, he treated the continuity between life and matter as a fundamental principle, seeing no ontological divide between the animate and inanimate. His approach was thus not only anti-dualist but also anti-metaphysical, anticipating the methodological naturalism that would come to dominate modern science.
La Mettrie’s materialism diverges sharply from thinkers such as Descartes, who saw animals as automata but preserved the human soul as an immaterial, divine element. He also differed from Spinoza, whose monism admitted a kind of spiritualised materialism; La Mettrie rejected even this. His originality lies in his insistence that life, consciousness, and identity are reducible to matter and motion, without appeal to any transcendent reality. In this sense, he can be seen as a precursor to later scientific naturalists and neuroscientific reductionists such as Paul Churchland, while his audacity foreshadowed the scepticism of Nietzsche and the provocations of Freud.
Hedonism and the Ethics of Pleasure:
La Mettrie made a unique contribution to moral philosophy by developing a thoroughly materialist and hedonistic ethics, arguing that pleasure is the natural and rational goal of life. Unlike ascetic or duty-based moralities, his ethics stem from the biological constitution of human beings and the functional needs of the body. He held that what we call “virtue” often arises not from divine command or rational duty, but from the individual’s pursuit of physical and emotional well-being. In Discours sur le bonheur, he celebrates pleasure not as mere indulgence but as a legitimate and healthy component of human life.
This theme includes several crucial aspects. First, La Mettrie contends that the pursuit of happiness should be personalised and adjusted to individual temperaments and capacities. There is no universal good life—what pleases one may displease another. Second, he frames pleasure not as the enemy of reason but as its ally, arguing that a rational person will naturally seek balance, health, and joy. Third, he introduces a provocative idea: even so-called “vices” can serve human well-being if moderated correctly. This relativism set him apart from the absolutist frameworks of Kantian ethics or Christian morality.
While La Mettrie’s hedonism draws on Epicurean thought, it is more radical in its grounding in physiology and its rejection of any metaphysical postulates. Unlike Epicurus, who still posited the need for mental pleasures and tranquility over bodily pleasure, La Mettrie refused to elevate the mind over the body. He also rejected the stoic ideal of virtue through suffering. In contrast to Enlightenment thinkers like Rousseau, who idealised virtue through civic engagement or natural goodness, La Mettrie’s ethics are grounded in empirical reality and physiological necessity. This biological relativism remains relevant in debates over subjective well-being, moral pluralism, and the science of happiness.
Human-Animal Continuity:
La Mettrie was among the earliest philosophers to argue forcefully for the continuity between humans and animals, both in physical structure and mental capacities. He viewed humans not as qualitatively different from animals, but as more complex variations of the same biological principles. This theme undermines the traditional Western idea of human exceptionalism, which saw rationality, language, or morality as uniquely human attributes. In his work, animals are not mindless automatons (as Descartes suggested), but conscious beings with sensitivity, memory, and even basic reasoning skills.
Three aspects stand out here. First, La Mettrie argued from anatomical and physiological parallels—he noted that both humans and animals share similar nervous systems, suggesting continuity in their capacities for sensation and emotion. Second, he posited that behaviour in both humans and animals could be explained mechanistically, via the same principles of stimulus and response. Third, he contended that the attribution of “soul” to humans but not animals was an arbitrary distinction driven by theological bias rather than scientific evidence.
This stance positioned La Mettrie against both religious orthodoxy and Cartesian rationalism. In contrast to Descartes, who used the doctrine of human uniqueness to justify animal cruelty, La Mettrie’s view offered an implicit defence of animal welfare. He also anticipated Darwinian evolution in his belief in the common origin and structure of living beings, even though he lacked the theoretical tools of natural selection. While thinkers like Locke admitted animals had sensation, they often denied them reflection or reason. La Mettrie, however, blurred these distinctions entirely, anticipating the contemporary debate about animal cognition and moral status.
Mechanistic View of Life and Consciousness:
Central to La Mettrie’s philosophy is the mechanistic view of life: the idea that living beings, including humans, are composed of physical parts functioning according to natural laws, much like machines. This vision extended not just to physiology but to consciousness itself, which he viewed as an emergent property of organic complexity. In L’Homme Machine, he presents the brain as an organ whose functions are no different in principle from those of the liver or the heart. He likened the body to a self-regulating automaton, capable of movement, sensation, and thought without need for any spiritual or supernatural element.
The mechanistic theme includes three principal dimensions. First, La Mettrie argued that all mental faculties—imagination, memory, reason—are traceable to brain activity and bodily organisation. Second, he viewed even emotions and moral sentiments as products of mechanical responses to environmental stimuli. Third, he considered consciousness itself as a function of highly organised matter, with no need to invoke immaterial explanations. This bold position foreshadowed later developments in neuroscience and artificial intelligence, especially the view that mental functions could, in principle, be replicated in non-biological systems.
La Mettrie’s mechanistic outlook set him apart from thinkers like Leibniz, who maintained that material machines could never explain perception. He also differed from Newtonians who, while advocating mechanical laws in physics, were hesitant to extend them to the mind. La Mettrie went further than Hobbes, who had also seen thinking as a form of motion, by grounding his view in medical evidence and comparative biology. His originality lies in his refusal to draw arbitrary boundaries between mechanical causality and inner life. Today, his work resonates with functionalist and physicalist theories in philosophy of mind, which continue to probe the machine-like nature of cognition.
Anti-Religious and Anti-Metaphysical Critique:
La Mettrie was a fierce critic of religious dogma and metaphysical speculation. His writings often contain scathing attacks on theologians and metaphysicians, whom he accused of cloaking ignorance in obscure language. For him, religious doctrines were not only false but harmful, encouraging guilt, repression, and the denial of bodily pleasures. He sought to replace theological explanations of the world with naturalistic, empirical accounts. His polemic was not limited to Christianity but extended to all forms of spiritualism and metaphysical idealism that evaded testable reasoning.
This critique operates on three levels. First, La Mettrie challenges the logical coherence of religious claims, especially the notion of an immaterial soul or divine purpose. Second, he targets the social and psychological consequences of religion, arguing that it cultivates fear and obedience rather than understanding or happiness. Third, he critiques metaphysical philosophy for its abstraction and detachment from the realities of human physiology and experience. In place of these traditions, he proposes a grounded, scientific, and hedonistic worldview based on evidence and individual well-being.
La Mettrie’s anti-religious stance places him within a radical Enlightenment tradition alongside figures like d’Holbach and later Feuerbach. Yet he is even more provocative in his consistent attempt to biologise all aspects of life, including ethics and psychology. Unlike Voltaire or Rousseau, who retained deistic or spiritual tendencies, La Mettrie sought a complete severance from religious thinking. His original contribution lies in his commitment to bringing philosophical inquiry entirely within the bounds of nature, a move that prefigures modern secular humanism and scientific atheism. His work serves as a philosophical antecedent to contemporary critiques of religion from figures such as Richard Dawkins and Sam Harris, though with a unique eighteenth-century audacity.
4) La Mettrie as Materialist
Julien Offray de La Mettrie’s legacy as a materialist thinker is foundational to understanding his radical place in the Enlightenment. At a time when dualistic and metaphysical explanations still dominated the intellectual landscape, La Mettrie advanced a bold, uncompromising vision: that all human experience, thought, and behaviour could be explained through material processes. He argued that the soul, the supposed seat of consciousness and morality, was nothing more than the function of the body’s physical organs. This reduction of mind to matter not only upended theological and philosophical orthodoxy but also anticipated many of the fundamental principles of modern scientific thought.
His most infamous work, L’Homme Machine (“Man a Machine”), published in 1747, encapsulates this materialist viewpoint. In it, La Mettrie asserts that humans are complex automata—biological machines whose mental and physical functions are entirely determined by natural laws. He rejected Cartesian dualism outright, insisting that thought does not stem from a separate, immaterial soul but from the organisation and activity of the brain. Unlike Descartes, who maintained a sharp distinction between the thinking soul and the extended body, La Mettrie posited a seamless continuity. For him, the brain secretes thought just as the liver secretes bile.
This mechanistic view of the human being was not simply metaphorical. La Mettrie genuinely believed that physiological processes such as digestion, circulation, and nervous excitation directly affected a person’s mental life. His training as a physician deeply informed this belief. He drew upon case studies, empirical medical knowledge, and personal observation to support his arguments. For example, he pointed out that illness, fatigue, or intoxication could dramatically alter one’s perceptions and thoughts, thus undermining any notion of an independent, immutable soul. In doing so, he brought philosophical inquiry into the domain of clinical observation and material science.
La Mettrie’s materialism also extended to animals, whom he saw as sharing the same physiological and psychological principles as humans. By removing the soul from the equation, he asserted the continuity between human and animal life. The mechanistic processes that generate sensation, thought, and even rudimentary reason are not exclusive to humans. In this regard, he anticipated later developments in evolutionary biology and comparative psychology. His insistence on the natural similarity between species challenged prevailing views of human uniqueness and implicitly undermined the theological claim of man as a divine creation.
Another key dimension of his materialism lies in his rejection of metaphysics. La Mettrie was deeply sceptical of abstract philosophical speculation that lacked empirical grounding. He believed that metaphysics was a remnant of theological thought, serving no practical or explanatory function in understanding the human condition. He dismissed concepts such as innate ideas, eternal truths, and immaterial substances as products of superstition and scholastic obscurantism. For La Mettrie, only what could be observed, measured, and explained by natural laws was worthy of serious philosophical attention.
Despite the radical nature of his claims, La Mettrie did not entirely isolate himself from other materialist traditions. He built upon earlier thinkers such as Hobbes, who also saw thought as a form of motion, but went further in tying this to empirical physiology. He also diverged from Spinoza’s more abstract pantheism and from Locke’s empiricism, which still left room for a soul or spiritual substance. La Mettrie’s originality lies in his unapologetic affirmation of a thoroughly embodied mind—one with no hidden metaphysical remainder. In this sense, he paved the way for the secular, biologically-informed understanding of consciousness that would emerge centuries later.
Critics of La Mettrie often accused him of reducing humans to mere machines, thereby stripping life of meaning, morality, and dignity. However, he would likely have countered that true dignity lies in understanding ourselves honestly, without illusion. By seeing ourselves as natural beings, governed by material laws, we can better care for the body, enhance happiness, and discard harmful dogmas. In this way, his materialism is not merely reductionist but liberating—a call to ground ethics, medicine, and social life in the realities of human physiology.
5) His Legacy
Julien Offray de La Mettrie’s legacy is marked by his pioneering contributions to materialist philosophy, his rejection of the soul as a separate entity from the body, and his challenge to established norms in both science and religion. While his ideas were controversial in his time—often drawing condemnation from religious authorities and other intellectuals—his impact has grown over the centuries. His philosophy paved the way for subsequent generations of thinkers who took a more naturalistic view of human nature and consciousness. Today, his work continues to inspire discussions in fields such as neuroscience, psychology, and philosophy of mind, where debates about the relationship between mind and body remain central.
La Mettrie’s most significant legacy lies in his radical materialism, which anticipated the modern scientific understanding of consciousness. By asserting that the mind is nothing more than the function of the brain and that all mental processes are grounded in the physical, La Mettrie broke with centuries of philosophical thought, particularly the dualism of René Descartes. His position that human beings are essentially machines in a biological sense foreshadowed many of the arguments found in contemporary neuroscience. The idea that thought, emotion, and consciousness are not supernatural phenomena but rather emergent properties of brain activity is now a central tenet of cognitive science.
In addition to his contributions to the philosophy of mind, La Mettrie also made lasting contributions to the fields of psychology and physiology. His emphasis on the biological basis of human thought and behaviour encouraged later psychologists to adopt a more empirical, scientifically grounded approach to the study of the mind. The materialist view of the human being, which he promoted, is reflected in much of the research conducted today in areas such as neuropsychology, where the brain’s influence on cognition, emotions, and actions is continually explored. La Mettrie’s approach laid the groundwork for the behaviourist school of psychology, which emerged in the late 19th and early 20th centuries, and was closely linked to theories that rejected the introspective methods of earlier psychologists in favour of observable, measurable phenomena.
La Mettrie’s influence extended far beyond philosophy and science. In literature and political theory, his ideas about human nature and the rejection of divine explanations had a profound effect on the Enlightenment. Thinkers like Denis Diderot, Voltaire, and Baron d’Holbach, who shared similar materialist views, were influenced by La Mettrie’s work. His emphasis on human beings as biological entities and his critique of religion resonated with the broader Enlightenment project, which sought to challenge the authority of the church and promote reason, science, and secularism. In this way, La Mettrie’s legacy is inextricably linked to the rise of secular thought in Europe, which influenced the development of modern democratic and scientific societies.
Despite the radical nature of his materialism, La Mettrie was not without his critics, especially during his lifetime. His works were banned, and he faced harsh criticism from religious authorities who viewed his materialism as blasphemous. However, as the centuries passed and the scientific understanding of the mind and body evolved, La Mettrie’s ideas gained greater acceptance. His work now appears far less controversial, and in many ways, it aligns with contemporary understandings of neuroscience and psychology. However, his rejection of the soul and insistence on the mechanistic view of human beings still challenges many religious and metaphysical traditions. In this sense, his legacy remains one of defiance against the constraints of dogma and an insistence on seeing the world as it truly is—through the lens of reason and empirical observation.
One aspect of La Mettrie’s legacy that is often overlooked is his role in the broader development of biological determinism. His assertion that human beings, like animals, are governed by natural laws and biological imperatives laid the foundation for later thinkers who would explore how genetics, evolution, and environmental factors shape human behaviour. The idea that our thoughts and actions are not determined by an immaterial soul but by physical processes in the body and brain has had a profound impact on later social and political theories. In the 20th century, thinkers like B.F. Skinner and Richard Dawkins, with their focus on behaviourism and gene-centred views of evolution, echoed many of La Mettrie’s ideas about the human being as a product of biology and environment.
The impact of La Mettrie’s work can also be seen in the field of artificial intelligence (AI) and the philosophy of mind. His idea of the human being as a machine resonates with contemporary discussions about whether machines could ever be considered conscious or intelligent. The question of whether machines could one day replicate human cognition is rooted in the materialist assumptions that La Mettrie espoused, as his view of the human mind as a product of material processes set the stage for current debates in AI, robotics, and cognitive science. La Mettrie’s work, though centuries old, remains relevant to these modern debates, which grapple with issues of machine consciousness, the nature of intelligence, and the possibility of creating artificial beings that resemble humans in both mind and body.