The historian Jane Caplan called "certainly the most ambitious and interesting recent attempt to analyse the relations between the production of concepts and the history of society in the field of sexuality", but criticized Foucault for using an "undifferentiated concept" of speech and an imprecise notion of "power". The gay activist Dennis Altman described Foucault's work as representative of the position that homosexuals emerged as a social category in 18th and 19th century western Europe. The feminist wrote that Foucault rightly argues that, "what we have all along taken as the breaking-through of a silence and the long delayed giving of due attention to human sexuality was in fact the promotion of human sexuality, indeed, the creation of an internal focus for the individual's preoccupations." The historian wrote that Foucault is right to raise questions about the "repressive hypothesis", but that "his procedure is anecdotal and almost wholly unencumbered by facts; using his accustomed technique (reminiscent of the principle underlying 's humor) of turning accepted ideas upside down, he turns out to be right in part for his private reasons."
The philosopher , writing in (1986), rejected Foucault's claim that sexual morality is culturally relative and criticized Foucault for assuming that there could be societies in which a "problematisation" of the sexual did not occur. Scruton concluded that, "No history of thought could show the 'problematisation' of sexual experience to be peculiar to certain specific social formations: it is characteristic of personal experience generally, and therefore of every genuine social order." The philosopher argued that Foucault's rejection of the repressive hypothesis is more apparent than real, and that the hypothesis is not "abolished, but simply displaced" in , as shown for example by Foucault's persistent references to "the body and its pleasures" and to . The classicist Page duBois called "one of the most exciting new books" in classical studies and "an important contribution to the history of sexuality", but added that Foucault "takes for granted, and thus 'authorizes,' exactly what needs to be explained: the philosophical establishment of the autonomous male subject". The historian Patricia O'Brien wrote that Foucault was "without expertise" in dealing with antiquity, and that lacks the "methodological rigor" of Foucault's earlier works, especially .
In volume I of the History of Sexuality, Foucault applies this understanding of power to the subject of sexuality in order to challenge what he calls the ”repressive hypothesis.” Whereas in the traditional understanding, power is exerted to repress, silence, censor or erase sexuality, Foucault starts to conceive of sexuality as being an immediate effect of power. From this point of view, the most significant strategies of power in modern societies are not the exclusion of sexuality from discourse, but its regulation through the production of public discourses on sexuality. Foucault identifies an institutional incitement to speak about sex at the heart of modern western culture(s). It is in the multiplication of discourses on sexuality and the assumption that sex would reveal the truth of our innermost selves that the power-sexuality relation is realized. Foucault thus refutes the supposition at the heart of sexual liberationism that it is possible to revolutionize society by freeing our natural sexual selves. Foucault’s anti-essentialist arguments have been widely taken up by scholars working from within a constructionist point of view. They have further inspired the deconstructive endeavor of recent queer theorizing.
Scruton wrote in 2015 that, contrary to Foucault's claims, the ancient texts Foucault examines in are not primarily about sexual pleasure. Nevertheless, he found the second two volumes of more scholarly than Foucault's previous work. Scruton concluded, of the work in general, that it creates an impression of a "normalized" Foucault: "His command of the French language, his fascination with ancient texts and the by-ways of history, his flamboyant imagination and beautiful style - all have been put, at last, to a proper use, in order to describe the human condition respectfully, and to cease to look for the secret 'structures' beneath its smile."
In Part One, Foucault discusses the "repressive hypothesis", the widespread belief among late 20th-century westerners that sexuality, and the open discussion of sex, was socially repressed during the late 17th, 18th, 19th and early 20th centuries, a by-product of the rise of and society, before the partial liberation of sexuality in modern times. Arguing that sexuality was never truly repressed, Foucault asks why modern westerners believe the hypothesis, noting that in portraying past sexuality as repressed, it provides a basis for the idea that in rejecting past moral systems, future sexuality can be free and uninhibited, a "...garden of earthly delights".