Peter van Inwagen, in an influential paper and again in a recent book, has propounded an important argument for the incompatibility of free will and determinism. 1 Of the various replies that have appeared in response to his original paper, perhaps the most incisive is by David Lewis. 2 Although van Inwagen does not discuss Lewis in his new book (which was already at press by the time the paper appeared), he does elaborate upon his own original argument in a way which suggests a response to Lewis's critique. In this paper I shall set forth, and then evaluate, that response.
van Inwagen points out that his argument represents one way of refining the following line of reasoning, which he calls the Consequence Argument:
If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us. (ETW, p. 16) He presents two other elaborations of the Consequence Argument in his book, and observes that all three versions probably stand or fall together. Other defenders of one or another version of the Consequence Argument include Carl Ginet, James Lambl and David Wiggins. 3 Michael Slote has described well the deep family resemblances among the various formulations, and he too has suggested that the different versions probably all stand or fall together. 4 Thus, if Lewis is correct in his critique of the specific version we shall consider here, then the other versions are probably in trouble too. Conversely, if van Inwagen's most recent discussion provides the basis for an adequate refutation of Lewis, then Lewis-style objections to the other versions can probably be refuted as well.