Actually, I guess he's right. Arguably, the common sense definition of 'A -> B' is simply modus ponens. That is 'Given A and A->B, it follows that B'. It's the

Actually, I guess he's right. Arguably, the common sense definition of 'A -> B' is simply modus ponens. That is 'Given A and A->B, it follows that B'. It's then no longer obvious that A -> B is equivalent to ~A v B. Indeed, implication in IL is different from material implication even though IL has modus ponens.