This approach was known as the Method of Doubt but his rationale and approach have been a subject of controversy for years.He believed never to accept anything as the truth, which he could not accept as obviously true. Everything should be so clearly presented to the mind that there are no doubts left at all. Anything that can be doubted has to be rejected. Reasons to believe something should be ample. The second step is to divide the subject into as many divisions as possible or whatever would help him to understand it better. The third step involved directing his thoughts, taking one step at a time, to reach the underlying complex knowledge. At the end of this, his reviews were so comprehensive, his enumerations so complete, that nothing was left to doubt.The three steps adopted by Descartes is what is adopted in mathematics. He wanted to use this method to reach the truth in philosophy. S V Keeling argues that his method as above rests on three mental operations – intuition, deduction, and enumeration (cited by Burnham, 2006). These operations are based on human reason, on the ability to disseminate information, analyze, and review. Since it is based on the capability of the human mind, there is a risk of error due to faulty memory.In the Meditations on First Philosophy Descartes proves the existence of God and the immortality of the soul. He also brings out the real distinction between the mind and the body. He starts this by asserting the need to demolish everything completely and start again right from the foundations (AT 7:17). Although the first step was termed as skeptical his skepticism was not for the sake of doubting. He wanted to arrive at the truth through systematic analysis and discarding the untruth. Descartes defines knowledge in terms of doubt:I distinguish the two as follows: there is conviction when there remains some reason, which might lead us to doubt, but knowledge is a conviction based on a reason so strong.
Descartes’ Method of Doubt