Descartes's Theory of Modality

Abstract

Descartes propounded the allegedly strange, peculiar, curious, and incoherent doctrine that necessary truths are made true by God's voluntary act.' It seems to imply that God could have made necessary truths false, which entails that they are not necessary after all. Some of Descartes's interpreters have taken him in that way, as firmly implying that nothing is absolutely necessary or impossible.2 We all know, however, that if this doctrine runs free through Descartes's philosophical work it will do untold damage: many of his arguments have to be protected somehow from the thesis that socalled necessary truths are really contingent. Discussing an argument of Descartes's for the real distinction between body and mind, for example, Curley writes: If we were to invoke the doctrine of the of eternal truths, we might say that a really omnipotent being could cause the mind and body to exist apart even if that were not logically possible. But in the Meditations Descartes is careful not to invoke that extravagant conception of omnipotence, and we would do him no service by bringing it in.3 That typifies the kind of thing Cartesian scholars have felt forced to say, charitably shielding Descartes from his own splatter. This creation or voluntarism doctrine does not appear in the Meditations, the Discourse on the Method, or the Principles of Philosophy. Descartes first declared it in three private letters to Marin Mersenne, most of a decade before his first published work ap-