What was the great discovery of the postmodernists?

Group Gelitin, Vorm Fellows Function

That to endure banality we reflexively and prophylactically endow it with a hierophantic aura, finding depth in nonsense, imputing revelation to flagrant acts of profanation (the secret of Duchamp's readymade).

Postmodernism is the idolatry of the profane, the consecration of desacration, the aestheticization of the anti-aesthetic. It is the ideology of a society that has reached the limit of profanation and can only alleviate its self-disgust by turning disgust into a higher-order aesthetic category.

In the same vein, Deleuze made madness chic. For how else can a disordered society, uprooted from its foundational traditions, incapable of centering or grounding itself, countenance its madness? Only by turning madness into an ideal.