Abstract
More than two decades ago, Vann McGee presented an alleged counterexample to modus ponens (MP). Despite criticisms, it seems to have survived to date. In this paper, I will defend McGee's counterexample against the criticism by Bernard Katz, as a representative of a type of the defense of MP, which appeals to certain logical principles, or what I call the logical defense of MP. I will argue that his way of criticizing McGee, and therefore of defending MP, actually begs the question. I will conclude that, the logical defense of MP in general will inevitably beg the question, and hence is doomed to fail. (This paper, together with my (2009), constitutes a part of my project on indicative conditionals, which is itself a part of the larger project on the theory of knowledge and belief change.)
