 Central to the inference is the meditator’s effort to check the correctness of his belief, by means of his various faculties. The cases like these to which Descartes refers look to be those where conditions (i) and (ii) are both satisfied. Recall what Descartes writes in conjunction with the proof of the external material world: from “the very fact that God is not a deceiver” there is a “consequent impossibility of there being any falsity in my opinions which cannot be corrected by some other faculty supplied by God” (AT 7:80, CSM 2:55f). Perhaps, therefore, we can understand Descartes’ theistic solution to the Now Dreaming Doubt as building on the same rule he employs in his proof for the external material world.