This paper suggests that the appearance of circularity in descartes' arguments is due to a lack of precision in his statements of them, Rather than to any flaw in his reasoning. The clear and distinct perceptions presupposed in the demonstrations of the existence of God are not the same as those whose reliability depends upon the existence of god. He is presupposing the reliability only of those clear and distinct perceptions which are known through the light of nature and have (...) metaphysical certainty in that they cannot be imagined false even on the demon hypothesis. And the only clear and distinct perceptions whose reliability he is demonstrating are those which are not known through the light of nature with metaphysical certainty but are subject to metaphysical doubt on the demon hypothesis, Even though they have moral or psychological certainty. (shrink)