Comments Elsewhere

Noumena, I’m not claiming that pounding out a truth-table for (4) won’t show why it’s unacceptable as a premise (or, what amounts to the same thing, applying M.I. to transform (4) into ~G—>(P&~A), as I did above). I recognize that the argument, as formalized, is just unsound.

What I am suggesting is that the fact that (4) ever seemed plausible in the first place highlights one of the difficulties inherent in being trained to instinctively translate “if p, then q” into “p materially implies q” when you formalize your argument. The premise is intuitively true, but only as long as you’re just reading it as “if-then,” in one of the ordinary English senses, and not as “either not-P or A.”

And I think there may be a moral to the story as to how far strictly technical advances in logic, such as the introduction and intensive use of material implication in foundational logic, deserves the kind of metaphilosophical fanfare that it got early in the last century.