Bennett on Modus Ponens

摘要

Jonathan Bennett, in his (2003), says that for indicative conditionals the unrestricted form of modus ponens (MP) is not valid, but restricted MP is still valid. In this paper I argue that Bennett is wrong, that even the restricted form of MP fails for indicative conditionals. I will show this by constructing, from his own counterexample to other formal properties of indicatives, a counterexample which is immune to the types of criticism that Bennett launches against the famous counterexample to MP by Vann McGee. I will also show that this type of failure of MP can be confirmed visually by a new but natural reading of the Adams-style Venn diagram.