From Stephen Hicks’ book, Explaining Postmodernism: Skepticism and Socialism from Rousseau to Foucault:
Any intellectual movement is defined by its fundamental philosophical premises. Those premises state what it takes to be real, what it is to be human, what is valuable, and how knowledge is acquired. That is, any intellectual movement has a metaphysics, a conception of human nature and values, and an epistemology. . .
Metaphysically, postmodernism is anti-realist, holding that it is impossible to speak meaningfully about an independent existing reality. Postmodernism substitutes instead a social-linguistic, constructionist account of reality. Epistemologically, having rejected the notion of an independently existing reality, postmodernism denies that reason or any other method is a means of acquiring objective knowledge of that reality. Having substituted social-linguistic constructs for that reality, postmodernism emphasizes the subjectivity, conventionality, and incommensurability of those constructions.
This is among the reasons why, whenever engaging the subject of postmodernism, I like to ask not only why are we having this conversation, but how are we having this conversation, if language itself lacks a basis in objective reality?