h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Isn't post-modernism the theory that says that (for example) a science textbook has no more or less validity than a work of deliberate fiction?

No, or, maybe, yes.

Post-modernism really has nothing to say about text books unless the critic is talking about how dull or interesting it might be. Physicists are the only people competant to talk about the validity of physics text books.

A post-modernists might, however, notice that the text book was out of date before it was published but then so would any competant physicist.

If one is a fan of Bertrand Russel then the idea of a complete physics text is, of course, a joke, regardless of the current state of the science of physics.

This article is not anything to base your understanding of post-modernism on except insofar as it does point out that post-modernism is very much a portmanteu category of art that follows the modern period which is generally considered to have ended somewhere in the '50s. Needless to say, things have been going on in the last 50 years.

Barton

portmanteu, meaning what?