Abstract

I think that van Inwagen's argument is invalid because it equivocates on the modal auxiliaries. To give a quick idea of what I think has gone wrong, consider for comparison two arguments which are transparently invalid, though they superficially resemble Modus Tollens arguments: (a) If Lincoln was honest, he couldn't have pocketed the penny (such taking being dishonest). (b) But it is false that Lincoln could not have pocketed the penny: after all, he was not paralyzed and did not fail to realize that the penny was (slightly) valuable and would be his for the taking. (c) Therefore, Lincoln was not honest. (a') If determinism is correct, then if various past events had occurred earlier, the judge could not have raised his hand at the time of the execution (since doing so would be inconsistent with the behavior issuing from and predictable from those earlier events). (b') But it is false that the judge could not have raised his hand at the time of the execution: for he was not paralyzed or unconscious-- he certainly possessed the power to move his hand. (c') Therefore, since the various past events did occur earlier, determinism is not correct.