Descartes

According to Descartes, geometricians rarely show the falsehood of accepted truths and demonstrations. By contrast, philosophers typically show the falsehood of contentions without venturing to explore truth. Descartes closes the dedication pleading with the faculty of the Sorbonne that their support and influence is necessary for the Meditations to be seen as a successful refutation of skepticism Descartes opens his Meditations indicating his desire to have only true beliefs. One way to accomplish this is …

…speculative skeptic merely uncovers theoretical problems, and an actional skeptic continues by recommending a course of action. With religious beliefs in particular, actional skepticism was viewed as more dangerous as it might recommend that act as though there were no God. However, Descartes only proposes theoretical doubt. In any event, he revises his doubt so not to run counter to traditional Christian belief and, accordingly, proposes that an evil genius (and not God) deceives him.