ABSTRACT
Is modus ponens a valid form of inference for the ordinary conditional? In a recent article Vann McGee has surprisingly argued ‘no’ on the basis of some very interesting examples. (See ‘A Counterexample to Modus Ponens’ in The Journal of Philosophy, September 1985, pp. 462–71.) I disagree with McGee’s conclusion about modus ponens, but think that his examples should be used to make some important points about assumptions, beliefs, ordinary conditionals, and valid inference. These points will show that no real counterexamples to modus ponens have been given.
