Descartes was searching for a sure foundation of knowledge, a first certainty that could serve for both philosophy and science. Cartesian doubt is a method, that leads to certain and undoubted knowledge. Sensible doubt, the doubt of the dream and the metaphysical doubt. The sensitive is the one that leads us to not trust completely the senses and all that we learn through the senses.
The doubt of the dream is the one that shows us that we cannot be sure that we are awake or dreaming at that moment. What I have learned Descartes was not a crazy guy who suffered from an obsessive thought of doubt, but a philosopher who used doubt as weapon in his journey in search of the foundation of knowledge. Reading about Descartes methods of doubt I learned that are many types of knowledge, but the most important is that we cannot trust a hundred percent in all the knowledges that is passed to us (pag95, paragraph5). Descartes experiments with the piece of wax to prove what is conceived in his spirit about this body. Descartes approach shows the wax, this external body, subjected to sensitive experiments in its materials and substances – itself, the wax – is still only a wax Descartes admits that what remained for him in his spirit was the same wax: “It must be admitted that it remains, and no one can deny it”.
Surely it can be absolutely nothing of all that observed through the senses, for all things that fell under the palate, or the smell, or the sight, or the touch, or the hearing, are changed, and yet the same wax remains. Then he concludes that his senses have perceived the wax differently, but have something that remains; however, what remains of that body is the same wax. (page176, paragraph 3) What I have learned after reading Descartes is that he would apply to all corporeal bodies of the type of wax the same understanding, saving true men in the second situation: when he sees them through the window he understands that they are true men only by the power to judge that he resides in his spirit. Also learned that the only element which differentiates the body from bodily nature from the wax-piece of the body of corporeal nature of true men, is the power of critical thinking. About knowledge I learned that we do not have hundred percent sure about anything, that we need to doubt about everything people say because even our senses lie to us and the act of questioning that brought and made the world what It is now. The world is moved through out questions and visionary’s like Descartes that doubt and realized that the method of questioning things was the best way to find different answers and create critical thinking because if everyone had the same thoughts there would be no advance on the society nor even on scientific discoveries.