How Rational is Descartes’ Rationalism?

Abstract

One of Descartes’ dreams was to see Scholasticism dead and his philosophy take its place. This was not, as Monsieur de Sacy saw it, a matter of usurping the place of Aristotelian philosophy, but of providing a philosophy that satisfies the demands of Christian religion. To say this is of course tantamount to claiming that Scholasticism did not fulfill this task. Strange as it sounds, this is what Descartes sincerely believed.¹ What was wrong with Scholastic philosophy? Did it not serve Christian religion well for several centuries? Had not St. Thomas erected the most complete and most impressive philosophical edifice at the top of which is a God who is both the highest philosophical principle and the Biblical creator? One of Descartes’ objections to Scholasticism is that it did not defeat atheism and that its proofs for the existence of God and of the immortality of the soul are at best mere demonstrations that the truths of religion are not contradictory to reason. Descartes’ intention — as he states in his “Letter to the Sorbonne” — was to make them rational in the literal sense of the word. His proofs were supposed to follow from reason alone. What makes a belief “rational,” according to Descartes, is the fact that it can be transformed into a perception of such force that the human mind cannot but assent to it. Accordingly, the propositions “God exists” and “the human soul is immortal” are rational the same way the proposition 2 + 2 = 4 is.² What Descartes’ project boils down to is a method that separates truths that are indubitable from those that are not.

There appeared a powerful and bold genius in France who decided to shake off the yoke of the Prince of the Schoolmen. This new man came to tell people that to become a philosopher it is not enough to believe; one must think. Antoine Guénard, S.J., Esprit philosophique (1755)