Those who would read the following should really have first read the first part, posted here on March 28th. I'm going to dive into the middle of material today without reviewing that. Ready? Let's go. How have defenders of a middle choice (between true and false, EVEN for some well-formed propositions) defended that possibility against C.I. Lewis' critique? Well, to begin, they note that any effort to prove something involves premises. To the extent that the law itself (we will call it LEM for short) is supposed -- as it is supposed by many -- to be a foundational premise in logic, it of course cannot be proven. If Lewis has actually proven LEM, it must have been by discovering other deeper premises, and turning LEM into a lemma, so to speak, a steppingstone on the path from some important truths to others. In fact, the Lewis "explosion argument" takes it as a premise that every sentence entails the disjunction of itself and any other sentence. This is kno...