 If even clear and distinct perception is subject to doubt, how is the meditator to make progress? How can he construct arguments in the effort to solve the sceptical problem? This brings into focus the issue of whether Descartes’ procedure is viciously circular. For it seems that in the very process of arguing for a truth rule, Descartes is already employing that very rule. For now, we’ll set side this issue of circularity (returning to it in  Section 6).