On Descartes Meditations I & II Descartes uses his Meditations on First Philosophy to consider one of philosophy s greatest questions: what is truth He dedicates this writing to outlining a rational, logical process of determining the answer, as well as his own conclusions in the matter. In book I, Descartes sets up the conditions for his search to the answer of what is true. He sets forth the somewhat radical notion that one must achieve a complete and total doubt if one is to accomplish this search. The reasoning behind this is that anything which is completely and totally true will survive even the most skeptical of doubts. Descartes seeks that one stationary point upon which to rebuild the whole of knowledge.
The question though is why should he undergo anything so extreme Can he not trust and have faith in what he has known all along Descartes embarks on this search precisely because he cannot trust his education to this point. When one finds that a belief is false, such as he had, then how can one believe in anything Therefore, he postulates, everything that one has previously believed in must be subject to doubt- everything. Book II is where the search for the one undeniable truth begins. It is here that he makes that infamous statement "cogito ergo sum," or, "I think, therefore I exist." What he really means by this is that no matter how much he doubts, no matter how much he may be deceived, he is indeed there to doubt or to be deceived.
That he exists is absolutely unshakable for as long as he is thinking. This point having been found, Descartes begins to rebuild the whole of his knowledge very slowly and carefully. He begins with the question of the nature of his existence and concludes that he is a thinking thing. The rest of the Meditations will be spent on the reconstruction in his mind of all that is real.
Descartes has in the first two book laid out his basis for determining what is true in the world, and he takes the reader through the first steps with him. He has discovered that one static point by which he plans to move the world.