The reason behind postmodernism’s contempt for propositional truth is not difficult to understand. A proposition is an idea framed as a logical statement that affirms or denies something, and it is expressed in such a way that it must be either true or false. There is no third option between true and false. (This is the “excluded middle” in logic.) The whole point of a proposition is to boil a truth-statement down to such a pristine clarity that it must either be affirmed or denied. In other words, propositions are the simplest expressions of truth value used to express the substance of what we believe. Postmodernism, frankly, cannot endure that kind of stark clarity.

– John MacArthur