ABSTRACT
The most central and familiar lines of argument of the Meditations, Rene Descartes professes to perceive the following propositions clearly and distinctly. Descartes's very sincerity in promulgating it is under a cloud. Considering just what is at stake in Descartes' concern with clear and distinct perception will help to identify more fully the source of fascination his argument evokes. Descartes is sometimes thought to have advocated a kind of lunatic apriorism, according to which a person might spin all of philosophy and all of science out of his own head without ever needing to turn to perceptual data. The precise value and import of consistency proofs, particularly in an unlimited context such as one in which Descartes operates, are difficult to specify exactly. It might perhaps be desirable, instead of construing his argument as attempt to prove the consistency of reason, to understand Descartes as attempting just to establish that there is no reasonable ground for doubting that reason is consistent.
