Preservation, Commutativity andModus Ponens: TwoRe- cent Triviality Results

We then turn to a recent u-turn on his part, in which he winds up rescinding his commitment toModus Ponens, on the grounds of a tension with the rule of Import-Export for conditionals. Here we offer an important positive contribution to the literature, settling the following crucial question that Bradley leaves unanswered: Assuming that one gives up on full-blown Modus Ponens on the grounds of its incompatibility with Import-Export, what weakened version of the principle should one be settling for instead? Our discussion of the issue turns out to unearth an interesting connection between epistemic undermining and the apparent failures of Modus Ponens in McGee’s famous counterexamples.