The central thesis of Madness and Civilization is that “madness” has not historically been a fixed concept in Western European thought, but rather one that has mutated in response to changing social conditions. Foucault traces the origin of the concept to the Late Middle Ages and ends in the mid-19th century, with the bulk of his analysis addressing the Early Modern period (which he deems the Renaissance and the Enlightenment). At the starting point of this timeline, he asserts, “madness” did not exist as a coherent idea, and at its end point it had transformed into a notion of mental illness. Between these two moments when “madness” does not exist as a social concept, is a “madness’s” heyday; during the Renaissance, and especially during the Classical Age, Foucault understands madness to have been a societal fixation in Western Europe.

Foucault characterizes the Middle Ages as a period so preoccupied with the ostracizing those afflicted with leprosy that they did not have or need a coherent formulation of “madness.” In this sense, the Middle Ages serve as an era of pre-”madness” that provides contrast with all of the constructions of “madness” that followed it. With the onset of the Renaissance, Foucault asserts that diminishing numbers of people with Hansen’s disease shifted the Western European fixation with defining an outcast community towards defining and othering “madness.” The definition that Renaissance society arrived at was a disturbing equivalence between “madness” and humanity: “When man deploys the arbitrary nature of madness, he confronts the dark necessity of the world; the animal that haunts his nightmares and his nights of privation is his own nature” (33). By this definition, a full othering of the “mad” had not yet occurred, but would eventually be enabled by forcible confinement in the 17th century.

Enlightenment society redefined “madness” as a form of animality, rather than humanity. Foucault synthesizes, “The animality that rages in madness dispossesses man of what is specifically human in him; not in order to deliver him over to other powers, but simply to establish him at a zero degree of his own nature” (83). This idea of the “madman” as an animal justified and was justified by dehumanizing displays of prisoners in a cyclical manner. 

Ironically, Foucault posits that this dehumanization on a societal scale is what eventually allowed for the development of medical methodologies that rehumanized mentally ill populations. “The physician could exercise his absolute authority in the world of the asylum only insofar as, from the beginning, he was Father and Judge, Family and Law,” he explains, “his medical practice… being no more than a complement to the old rites of Order, Authority, and Punishment” (279). This cause-and-effect relationship between different concepts of “madness,” as put forward by the author, creates an impression of history as a progressive process that builds upon but does not fully erase past failures; humane medical treatment of the mentally ill is possible only because of historically inhumane treatment, and in that sense can never be fully humane.