Descartes purports to prove the existence of an all-perfect creator. The most prominent philosophical reply to such “proofs” is the problem of evil. In turn, theists counter with theodicies – efforts at showing that God and evil are compatible. Securing a successful theodicy is essential to the Meditations, because Descartes makes divine benevolence the cornerstone of his epistemology. Indeed, the Meditations develops two theodicies. Philosophers generally distinguish moral evil (i.e., evil arising from voluntary human choices) and natural evil (i.e., evil arising from natural causes). Descartes’ Fourth Meditation theodicy addresses a form of moral evil arising from judgment error. His Sixth Meditation theodicy addresses a form of natural evil arising from sensory error.

The Fourth Meditation theodicy arises in the context of an inquiry into the nature and causes of judgment error. The traditional problem of evil derives from the fact of suffering in conjunction with the theistic supposition of a creator who is both all-powerful and all-good. Stating the problem in a form tracing to Epicurus, Hume (2007, 74) writes (of the creator): “Is he willing to prevent evil, but not able? Then is he impotent. Is he able, but not willing? Then is he malevolent. Is he both able and willing? Whence then is evil?” Descartes first introduces the problem in the First Meditation, in the course of his program of methodic doubt. With the external world in doubt, and thereby all external suffering (see body, proof of the existence of), Descartes frames the problem in terms of judgment error stemming from the possibility of an “omnipotent God” who is a deceiver – for example, allowing me to “go wrong every time I add two and three.” A passing effort at rebutting the doubt is made, on the grounds that “perhaps God would not have allowed me to be deceived in this way, since he is said to be supremely good.” Yet the supposition of a God who is both omnipotent and supremely good seems incompatible with error: “If it were inconsistent with [God's] goodness to have created me such that I am deceived all the time, it would seem equally foreign to his goodness to allow me to be deceived even occasionally; yet this last assertion cannot be made” (AT VII 21, CSM II 14).