 At times, Descartes appears to endorse the PSR. For example, he argues for the existence of God in the third Mediation on the basis of the principle that there must be at least as much reality in the cause as in the effect. And he justifies this causal principle by claiming that “Nothing comes from nothing”. This appears to make him as much an adherent of the PSR as Parmenides who, as we have seen, argues for his conclusions on the same basis. But elsewhere Descartes claims that God creates the eternal truths, such as mathematical and metaphysical truths (Letters to Mersenne, April 15, May 6, and 27, 1630; Fifth Replies, AT 7:380, CSM 2:261). Moreover, he claims that God creates these truths by an act of will which is free and indifferent. Thus there can be no reason for God’s will to create any of these truths. If the act of will by means of which God creates the mathematical and metaphysical truths is contingent and yet has no sufficient reason according to Descartes, then his philosophy is deeply antithetical to the PSR. Of course, Descartes, like many of the others we have discussed may have endorsed a restricted version of the PSR. But the most natural and rationalistically acceptable restriction would be to contingent truths. Descartes’ doctrine of the creation of the eternal truths holds that there is at least one contingent truth (the act of will by means of which God creates the eternal truths) which lacks a sufficient reason.