Bad writing, deliberately so.

From Christopher Butler, Postmodernism: A Very Short Introduction (Oxford UP, 2003):

Postmodernists, who were rightly enthusiasts for ‘liberating’ ethical and political doctrines, were at the same time immensely dependent on the extraordinary prestige of these new intellectual authorities, whose influence was not a little sustained by their heavy reliance upon a neologizing jargon, which imparted a tremendous air of difficulty and profundity to their deliberations and caused great difficulties to their translators. According to the American philosopher John Searle:

Michel Foucault once characterised Derrida’s prose style to me as ‘obscurantisme terroriste’. The text is written so obscurely that you can’t figure out exactly what the thesis is (hence ‘obscurantisme’) and then when one criticises this, the author says, ‘Vous m’avez mal compris; vous êtes idiot’ (hence ‘terroriste’).

New York Review of Books, 27 October 1983

The often obscure, not to say obfuscating, modes of speech and writing of these intellectuals were sometimes even intended to signify a defiance of that ‘Cartesian’ clarity of exposition which they said arose from a suspect reliance upon ‘bourgeois’ certainties concerning the world order. Roland Barthes, discussing 17thcentury French literature, says that:

Doubtless there was a certain universality of writing which stretched across to the elite elements of Europe living the same privileged life-style, but this much-prized communicability of the French language has been anything but horizontal; it has never been vertical, never reached the depths of the masses.

Roland Barthes, Oeuvres Complètes vol. I (1942–65)

A suggestive punning word-play was preferred to a plodding and politically suspect logic, and the result was a theory which was more literary than philosophical, and which rarely if ever came to clear or empirically testable conclusions, simply because it was so difficult to be sure about what it meant. This placed a very satisfying burden of translation exposition and defence upon the followers of the masters of theory. The French masters wrote in a resolutely avant-gardist way against the clarity of their own national tradition. It is the thousands of echoes and adaptations, and unsurprising misunderstandings, of their obscure writings that have made up the often confused and pretentious collective psyche of the postmodernist constituency.