=Induction――Provisional Doubt――The Ultimate Certainty of Consciousness.= The philosophical proclamation of Descartes was characteristically French, for he demanded the same return to an uncorrupted nature for the understanding that Rousseau many years later demanded for the heart. The first step of Descartes was also French in its demand for absolute clearness, which from his youth had shown him to be so passionately fond of mathematics. The way to such clearness is through provisional doubt. Let us purify the understanding by delivering it of the rubbish of traditional opinions, taken upon the say-so of others. By this negative induction of received knowledge, let us see if there is anything positive and certain. In Descartes’s _Meditations_, in “a dramatic dialogue with himself,” he portrays his own intellectual struggle to gain uncontaminated truth. He makes an induction of all kinds of knowledge and challenges each as it appears. Nothing is to be accepted as true until it has proved itself true. All facts are subjected to rigid scrutiny. Descartes doubts the testimony of the senses, the existence of the material world, the existence of God. But this induction is provisional, even if it is radical. While none of the usually accepted truths are found by him to be undeniable and absolute, yet Descartes has an ulterior purpose in challenging them. Greek skepticism had no further end than doubt, while at the other extreme Anselm and the orthodox scholastics had refused to doubt at all. The method of Descartes is contrasted both with that of Anselm and with that of the Skeptics, for he doubts in order that he may know. _Dubito ut intelligam._ Doubt is necessary, but only as a means to an end; and that end is knowledge. Descartes proclaimed for the modern individual the privilege and the duty of rationalizing his own beliefs.