Issues concerning circularity figure prominently in epistemology, finding a place in discussions of topics ranging from the Cartesian circle, to the problem of the criterion, to knowledge of the reliability of ways of forming belief.

Descartes and Cartesian Circles

Issues of circularity arise in the works of René Descartes. In his Meditations, in his search for items of certain knowledge (indubitable items given even the possibility of massive deception), Descartes finds that he is certain that he is a thinking being. But what makes this certain for him? The only explanation he finds is that he clearly and distinctly perceives this fact. Furthermore, he finds that clear and distinct perception could not be the source of such certainty if such perceptions could be false. So, he tentatively concludes, whatever is clearly and distinctly perceived is true. But does he really know this general principle...