In the first Meditation
In the first Meditation, Descartes employs ‘the method of doubt.’ He wants to find a foundation of knowledge that is so secure, it can stand up against the doubts of the strongest skepticism. Descartes presents what is, in effect, a dialogue between a person employing common sense and a skeptic. The person relying on common sense believes that there are various reliable sources of knowledge, while the skeptic claims that there is no secure foundation for knowledge. The skeptic in this debate acts in the same way as an ancient (historical) skeptic. That is, the skeptical procedure to isolate internal contradictions in the positions of those who claim that they know things.