Enlightenment philosopher, René Descartes, set out to establish what could be known with certainty, untainted by a deceiving demon. With his method of doubt, he rejected all previous beliefs, allowing only those that survived rigorous scrutiny. In this essay, Leslie Allan examines whether Descartes's program of skeptical enquiry was successful in laying a firm foundation for our manifold beliefs. He subjects Descartes's conclusions to Descartes's own uncompromising methodology to determine whether Descartes escaped from a self-imposed radical skepticism.