Descartes, Circularity, Method

The 'Cartesian Circle' refers to the alleged circularity of the reasoning with which Descartes appears to argue both that he is certain that God exists because God exists, and that God exists because he is certain that God exists. However, if there is any circularity involved, it is not specific to the theological content of the argument; rather it is a characteristic of Cartesian methodology in general. His method entails three premises. First, every appearance A in consciousness has a cause X. Second, if an effect exists, then so too does its cause. Third, if it is impossible for A to have any other cause than X, then X is certain. So, if X is certain, it is the cause of A, and, therefore, it exists. Conversely, if X exists, and it causes A, then it is impossible that A have any other cause than X, and, thus, X is certain. So, the alleged Cartesian Circle entails a specific application of a methodology comprised of an Epistemological premise, an Ontological premise, and a Modal premise, respectively. Unfortunately, Descartes breeds confusion by often expressing the Modal proposition 'It is impossible to doubt X' in Epistemic terms, 'I am certain that X'. Hence, his 'I am certain that God exists', may, more properly, mean, 'God necessarily exists', which might defuse the charge of circularity.