The Cartesian Circle

I have been mistaken, more than once. Perhaps I could be always mistaken. The world I seem to see around me might be a complete delusion. I can doubt everything -- except that when I am doubting, I must exist, at least as a doubting, thinking thing. This I see clearly and distinctly. But how do I dispel my doubts about the external world?

If I doubt, I realize that I am not perfect. But where did I get this idea of perfection? Since no effect can be as great as its cause, the cause of my idea of perfection can only be actual perfection itself, i.e. God. A perfect God would have no need of deception, so - since he created me and my reason -- I can trust my clear and distinct ideas. So my doubt is overcome, and I can go on with my worldly existence.

Suppose I assure you that you can trust Brother Bovina, the famous psychic. You ask how I know this, and I explain, "Why, he told me you can trust him." The circularity of the Brother Bovina example is obvious. Is there a similar circularity in Descartes' argument about "clear and distinct ideas?"

Another question: Could I be always mistaken?

Bibliography

Descartes, Rene, Philosophical Works of Descartes, Dover Publications, Inc., New York, 1931, two volumes.