Abstract

We aren’t particularly sympathetic to modal realism (MR). Still, it isn’t clear to us that David Lewis argues for it in the wrong way. “The hypothesis is serviceable,” he says, “and that is a reason to think that it is true” (1986, p. 3). Let’s grant him the first claim: MR is serviceable, which is to say that it allows us “to reduce the diversity of notions we must accept as primitive, and thereby to improve the unity and economy of the theory that is our professional concern – total theory, the whole of what we take to be true” (1986, p. 4). Our interest here is in the second claim, the thesis to the effect that a hypothesis’s being serviceable can provide reason to believe it. A number of philosophers maintain that this latter is false; others insist that it’s of no help to Lewis. So on one basis or the other, they conclude that Lewis’ argument for MR doesn’t get off the ground.1 We disagree. Our aim here is to show that there isn’t a cogent objection to Lewis’ use of serviceability that doesn’t rely a premise that he is justified in rejecting.