Encyclopedia of Philosophy: The Doubt and the Cogito - DESCARTES

Descartes insisted that the first task in philosophy is to rid oneself of all prejudice by calling in doubt all that can be doubted. The second task of the philosopher, having raised these doubts, is to prevent them leading to scepticism. This strategy comes out clearly in Descartes' Meditations. As the title suggests, the work is not intended to be read as an academic treatise. It is meant to be followed in the frame of mind of a religious retreat, such as St Ignatius Loyola's Spiritual Exer¬cises. It is to provide a form of thought therapy, detaching the mind from false approaches to the truth in the way that religious meditation detaches the soul from the world and the flesh.  In this intellectual discipline, the deliverances of the senses are called in ques¬tion, first by considerations drawn from sense-deception, and then by an argument from dreaming.