IAM ATTRIBUTING to Descartes a specific and unified way of using the doubts of the First Meditation to establish the principles of First Philosophy. This understanding of the method of doubt intersects with two large philosophical problems, one old and one not so old. The problem of the “Cartesian Circle” was first raised by Mersenne (2:89; AT 7:124–25) and Arnauld (2:150; AT 7:214) in their objections to the Meditations. More recent is the problemof characterizing and assessing “transcendental” arguments. I want to reflect on the method of doubt in connection with each of these, and then I will close by returning, as I have promised I would, to the relation between philosophical inquiry and the perspective of common sense.
Here is the apparent problemof circularity. In the First Meditation, Descartes presents the deceiving God scenario (or the fate-or-chance scenario) as a reason for doubting the truth of anything he grasps clearly and distinctly. Now, to be absolutely certain that his clear and distinct ideas are true, he must be absolutely certain that God exists and is not a deceiver. To be absolutely certain of that, he must be able to be absolutely certain of the premises from which he draws that conclusion. He grasps these premises clearly and distinctly, but to claim to be absolutely certain that they are therefore true, he must be absolutely certain that God exists and is not a deceiver. His circular bind, then, is that he can be absolutely certain about God only if he is already absolutely certain about clear and distinct ideas, and he can be absolutely certain about clear and distinct ideas only if he is already certain about God. Arnauld raises the difficulty