 To see this, notice that, if Descartes does not allow the atheist to be able to acquire knowledge through clear and distinct perception, he will fall into the so-called Cartesian Circle. This problem, first identified by Arnauld in the Fourth Set of Objections, arises if Descartes holds both of the following claims: (i) I can know that my clear and distinct perceptions are true only if I first know that a non-deceiving God exists, and (ii) I can know that a non-deceiving God exists only if I first know that my clear and distinct perceptions are true. Because knowing one thing is a precondition for knowing the other, and vice versa, I cannot know either of them. In fact, however, it does not look as though Descartes does fall into the circle. Although it is pretty clear that he is committed to (1)—in the Third Meditation, he says that, “if I do not know [whether there is a non-deceiving God], it seems that I can never be quite certain about anything else” (PW 2, p. 25)—there is no reason to take him to be committed to (ii). Descartes is willing to permit the meditator to use clear and distinct perceptions before knowing that they are generally true. The clearest example, of course, is the cogito; the meditator first comes to know that he exists as a thinking thing and only later comes to know that his knowledge of the cogito is grounded in its clarity and distinctness. The same, then, can be said for the meditator’s knowledge—grounded in some clearly and distinctly perceived causal principles—that God exists. In using those principles, the meditator does not first need to have the general knowledge that clear and distinct perceptions are true (see Van Cleve 1979).