Why doubt?
Realising that many beliefs he had accepted since childhood were false, Descartes set out to rebuild knowledge on an unshakable foundation. Unlike the sceptic, he used doubt as a method for reaching certainty.
Stages of doubt (First Meditation)
- Sense error: the senses sometimes deceive, so they cannot be fully trusted.
- The dream argument: there is no sure sign distinguishing waking from dreaming.
- The evil demon: an all-powerful deceiver might mislead us even about mathematics.
The cogito
Yet if I am deceived, I who am deceived must exist. "I think, therefore I am" from the Discourse became a first principle that no doubt can defeat. From it Descartes tried to re-establish God's existence and the external world.
Four rules and criticism
The Discourse sets out four rules: evidence, analysis, synthesis and enumeration. Critics raise the "Cartesian circle", since clear and distinct ideas prove God while God guarantees those ideas, and the problems of mind-body dualism.
References
- Descartes, R. (1637). Discours de la méthode. Leiden: Jan Maire.
- Descartes, R. (1641). Meditationes de prima philosophia. Paris: Michel Soly. (Eng. trans. J. Cottingham, Cambridge University Press, 1996)
- Williams, B. (1978). Descartes: The Project of Pure Enquiry. Penguin.