Michel Foucault was a French philosopher best known for his contributions to post-structuralism and postmodernism. Foucault is often considered one of the most influential philosophers of the 20th century, particularly due to the emergence of critical theory.
Foucault’s philosophical work focused on the idea that knowledge and power are inseparable. All ideas convey power that alters human behavior, and institutions primarily serve as organized attempts to manipulate individuals for particular ends. Foucault criticized historical Western classical-liberal norms for concealing power impositions under the guise of humanitarianism and rationalism.
Foucault’s politics were far-to-radical-left, though he spent little time thinking or writing about policy matters. He was briefly a member of the French Communist Party, but later became disillusioned with communism and socialism.
Paul-Michel Foucault was born in Poitiers, France to an upper-middle-class family. His father was a surgeon and his mother a housewife. Foucault attended Lycée Henri IV, one of the best high schools in France. He studied philosophy, including that of Hegel, Marx, Kant, Husserl, Heidegger, and Gaston Bachelard under Jean Hyppolyte, a Marxist teacher. 
In 1946, Foucault began attending Ecole Normale Superieure, an elite French university. He studied under Louis Althusser, a Marxist who recruited many of his students to join the French Communist Party. Foucault initially joined but grew disillusioned with class-based analyses, as well as the homophobia and antisemitism he witnessed in the Party, and so left after a few years. 
Foucault suffered from depression from an early age, likely stemming from his abusive father, high-pressure education, and social ostracization due to his homosexuality. In 1948, Foucault attempted suicide for the first time. 
Foucault graduated with a BA and MA in philosophy, and then began a Ph.D. in the philosophy of psychology. He focused on the relationship between patients and doctors based on his experience of staying in a psychiatric ward after his first suicide attempt. In 1961, he published his thesis, “Madness and Insanity: History of Madness in the Classical Age,” which argued that insanity was an invention of medical institutions that society uses to control aberrant individuals. He would later expand on his thesis over multiple books. 
After graduating, Foucault worked as a philosophy professor in universities throughout the United States and France, including the University of California, Berkeley; the University of Vermont; New York University; and College de France. He was considered an extremely popular professor with students and was known for his activism regarding mental health issues, racism, and prison reform. 
Foucault’s work is often cited as a crucial foundation for postmodernism, though Foucault himself rejected the term. Postmodernism is a philosophical reaction to eighteenth- and nineteenth-century modernism and the Enlightenment. While modernism is based on the use of reason to access objective truths contained within an absolute reality, postmodernists generally consider reason and reality to be either false or unknowable. Instead, postmodernists see the world through the lens of subjective relationships between individuals, groups, and society. 
Foucault’s work focused on interpretations of power and knowledge in society, which is generally known as “social constructivism.” He believed that knowledge was inseparable from power, and therefore entirely subjective. The truth of any given knowledge is irrelevant; all that matters is how the knowledge applies within a given system. For instance, Foucault viewed many modern institutions – prisons, mental health systems, the military, and so forth – not as endeavors to solve problems, but as covert means of controlling populations through the subtle manipulation of human psychology by the inculcation of particular knowledge. To Foucault, individuals have no fixed psychological nature, but rather are “subjects” constantly pushed and pulled by competing societal powers, including the government, families, social norms, and religion. 
Discipline and Punish: The Birth of Prison
Discipline and Punish, a history and analysis of the Western penal system, is one of Foucault’s most famous works. Foucault claims that the Western penal system has gradually moved from favoring public punishments based on retribution to private punishments based on ostensible rehabilitation (from public executions to prisons). The stated goal of the transition was to humanely reintegrate criminals into society rather than to condemn them to death. 
Foucault argued that the real purpose of this transition was for the state to develop methods of social control. Behavioral control methods crafted in prisons (such as the “panopticon”) have since been applied to other domains, such as the military and schools, to control the general population. Beyond sheer physical control, these prison-inspired reforms have also reshaped discourse to psychologically manipulate the population. For instance, the concepts of “reform” and “criminal” cause people to separate others into “good” or “bad” people, thereby allowing the state to ostracize non-conforming members of society. 
Biopower (or “biopolitics”) is a concept developed by Foucault which refers to states treating their populations as a natural resource to be cultivated and directed. For instance, governments might want to shift age demographics to sustain a large enough young and productive component of the populace to care for the older and non-productive part. Likewise, many states encourage high birth rates and young populations to develop soldiers for the military. 
Unlike authoritarian methods of population management like strict laws or censorship, biopower is based on shifting norms which are internalized by individuals. Rather, societal norms will naturally support biopower goals. For instance, non-reproductive sex was traditionally discouraged in societies because it distracted from reproductive sex which contributed to population replenishment. 
Foucault did not attempt to formulate coherent political views by traditional standards. He rejected attempts to prescribe political changes as being based within their contextual power structures. What political views he did express tended to be far- or radical-left, though his views evolved throughout his life. 
In college, he joined the French Communist Party for a few years, but left due to their views on homosexuality and Jews. In the mid-1960s, he worked in Tunisia and admired the political activism of his left-wing students.  In 1969, Foucault was one of the few faculty members to join a left-wing student protest against University of Vincennes, and allegedly threw stones at the police. At times, Foucault supported Marxism, Maoism, and spoke in favor of Ayatollah Khomeini, the radical Islamic cleric who took over Iran in the Islamic Revolution of 1979. 
However, Foucault rejected nearly all traditional political labels. He claimed to reject both the predominant liberalism of Western governments and the state socialism of the Soviet Union. He was particularly critical of Stalinism and the atrocities perpetrated on its behalf. 
In 1971, Foucault, Jean-Paul Sartre, Jacques Derrida, Simone de Beauvoir, and other leading French intellectuals signed a petition calling for the French government to decriminalize age-of-consent laws regarding sex between adults and minors.  In the same year, Foucault founded the Group for Information on Prisons, a left-wing criminal justice reform organization. 
In 1971, Michel Foucault and far-left philosopher Noam Chomsky engaged in a televised debate in the Netherlands. The discussion largely centered around human nature, with Chomsky taking the position that individuals have at least a partially fixed nature shared by all humans, and Foucault challenging that human nature was entirely dependent on social forces. At one point, Chomsky stated that people must act in accordance with “responsibility, sensitivity, justice, and law,” which Foucault then dismissed as “tokens of ideology” without legitimacy. After the debate, Chomsky called Foucault “totally amoral” for his complete rejection of traditional philosophical standards.