ly true. They are propositions which no rational mind can doubt. The second method is deduction, by which Descartes means orderly, logical reasoning of inference from self-evident propositions. Descartes said that the chief secret of method was to arrange all the facts into a deductive, logical system. Descartes wishes to build a system of philosophy based on intuition and deduction, a system that will remain as permanent as and true as geometry. Descartes sets forth three requirement for the foundations of this philosophy:
1) Its certainty must be such that it is impossible to doubt, it is self-evident to reason, it is clear and distinct.
2) Its certainty must be ultimate and not dependent upon the certainty of any other belief.
3) It must be about something which exists, and from it beliefs about the existence of other things can then be deduced (Lavine 93-95).
Self-evident propositions did not include ideas about the nature of things. Descartes said we could not deduce a priori
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