Descartes Cartesian Circle

Escape from the Cartesian Circle? In his third meditation, Descartes expresses doubts about whether he can be absolutely certain of things that seem “clear and distinct.” He finds it necessary to doubt whether even such obvious propositions as “Three plus two equals five” are true because there might be, he says, a supremely powerful deceiver who is causing him to “be deceived even about matters [such as “Three plus two equals five”] that [seem] most evident.” He goes on to make an argument for the existence of a perfect God, reasoning that if such a God exists, he cannot be a deceiver and will therefore make sure that Descartes is not deceived about things that seem to be true. The problem here is that Descartes seems to be reasoning in

This error of reasoning is known as the Cartesian circle. Many attempts have been made to extricate Descartes from this circle by interpreting him as saying something different from what I’ve outlined above. In this paper I will consider one of these proposed solutions to the problem. In doing so, I will follow the example of Dugald Murdoch and refrain from discussing any of Descartes’ other writings; I will restrict my discussion to the text of the Meditations itself, because, as Murdoch writes, “If Descartes was not begging the question, then it should be possible to show this largely on the basis of what he writes in the

He might assert that he knows by the light of nature that he is not deceived in believing things that he perceives by the light of nature. But this is blatantly circular. Or he might say that the truth of (2) is self-evident. But this won’t work, because the truth of “Three plus two equals five” is self-evident as well, and Descartes finds it necessary to doubt that proposition. Since Descartes considers it to be possible that he is deceived in believing self-evident propositions, he cannot appeal to self-evidence to justify believing that he is not deceived in thinking he can trust what he perceives by the light of