While this is an accurate statement, it’s also a tricky one. Other thinkers (e.g. Richard Lanham in The electronic Word would argue that postmodernism is not an entirely new phenomenon but rather an instantiation/variation of Sophist thinking. Unlike Deibert, who seems to see intellectual history as a linear movement, these thinkers argue that Western intellectual history since the Greeks has always oscillated between a Platonist (essentialist) and a Sophistic (relativist/antiessentialist) pole. I’m not sure what difference this second way of seeing postmodernism would make to Deibert’s argument, but I found it interesting that he cuts of his timeline at WWII.