The “repressive hypothesis” is found in Michel Foucault’s History of Sexuality vol 1, in which he examines the functioning of sexuality as an “analytics of power” related to the emergence of a science of sexuality (scientia sexualis) and the emergence of biopower. For Foucault, biopower is sort of like a technology of power, which is to say, a way of exercising power encompassing various techniques into a single technology of power. The distinctive quality of this political technology is that it allows for the control of entire popualations. It is thus essential to the emergence of the modern nation state, to modern capitalism, etc. Biopower is literally having power over other bodies, “an explosion of numerous and diverse techniques for achieving the subjugations of bodies and the control of populations”
The “repressive hypothesis” is so-called because the widespread belief that we have, particularly since the nineteenth century, “repressed” our natural sexual drives. He shows that what we think of as “repression” of sexuality actually constituted sexuality as a core feature of our identities, and produced a proliferation of discourse on the subject. This is the legacy of the Victorian age, where calling sex by its name was prohibited. The imperative of Victorian Era Christianity is this: not only will you confess to the acts contravening the law, but you will seek to transform your desire, your every desire, into discourse. Insofar as possible, nothing was meant to elude this dictum, even inf the words it employed had to be carefully neutralized.
We still have this highly-prolix Victorianism in our culture, and is present in our subjugation of sexuality on the level of language. It exists in the internal discourse of institution sand structures in our society. Foucault’s terminology here is discourse, which is generally considered to be an institutionalized way of thinking, a social boundary defining what can be said about a specific topic, or, as Judith Butler puts it, “the limits of acceptable speech” – or possible truth. Discourses are seen to affect our views on all things; it is not possible to escape discourse.
In the rest of his book he discusses all the sorts of effects one might expect from this sort of repression we have experienced in our culture, and still exists in cultural memory, repressing us still. It’s the sort of puritanism that says we must tell everything, not only consummated acts, but sensual touchings, all impure gazes, all obscene remarks.