Simplifying to the extreme, I define postmodern as incredulity toward metanarratives. This incredulity is undoubtedly a product of progress in the sciences: but that progress in turn presupposes it. To the obsolescence of metanarrative apparatus of legitimation corresponds, most notably, the crisis of metaphysical philosophy and of the university institution which in the past relied on it. The narrative function is losing its functors, its great hero, its great dangers, its great voyages, its great goal. It is being dispersed in clouds of narrative language elements – narrative but also denotative, prescriptive, descriptive and so on. Conveyed within each cloud are pragmatic valencies specific to its kind. Each of us lives at the intersection of many of these.
However, we do not necessarily establish stable language combinations, and the properties of the ones we do establish are not necessarily communicable.
Source: Jean-Francois Lyotard, The post-modern condition
* Postmodernism in a nutshell