Two of postmodernism’s original contributions, the unreliability of Cartesian science and the instability of language, are premised on sophomoric understandings. So writes John Ellis in ‘What Does Postmodernism Really Amount To?’.

Postmodernism’s components include skepticism, cultural relativism, the shortcomings of rationality, and neo-Marxism, all of which are unoriginal. Its attack on science and language are new.

…General skepticism about scientific knowledge [is postulated], for example, by the postmodernist Jean-François Lyotard, who advocated incredulity toward all such ‘meta narratives’. [In the 1860s Charles Sanders] Peirce put paid to that attitude in a devastating riposte. He argued that generalized doubt was impossible, because when we doubt something our doubt is grounded in specific knowledge. If you doubt a theory, it will be because you know something that causes your doubt. If you are skeptical of Darwinism and people ask you why, they’ll expect a specific reason for your doubt, and they won’t be satisfied with a theoretical rejection of all scientific narratives. Indiscriminate doubt is nothing but empty posturing.

Regarding the instability of meaning in language, French critic Jacques Derrida misread of Swiss linguist Ferdinand de Saussure. Saussure said the assignment of words to meaning was ‘arbitrary’ but that the meaning made sense in its context (e.g., 20C or 70F are both accurate measurements).

Because he misunderstood what Saussure meant by this second sense of ‘arbitrary’ Derrida jumped to the conclusion that meaning becomes unreliable and indefinite. This mistake was amplified by Derrida’s stylistic habit of dramatic verbal exaggeration. And so, for him, the absence of a reference that exists independent of language (what he called the ‘transcendental signified’) extends the domain and the play of signification infinitely. Meaning becomes indefinite, limitless, indeterminate. The play of signifiers is endless. But of course Saussure’s point was exactly the opposite — that the meaning of a term is created by its place within a system of terms and is specified within that system.