Descartes Descartes believed that we should ask what it would mean to know about reality, and to examine what reality meant. He claims that unless we know first whether our belief itself is justified we can't know. To determine whether our beliefs are justified, we have to be able to trace them back to a statement, belief, or proposition that cannot be doubted. Like many other philosophers the only true and believable facts are mathematical. But if achieved, such a proposition could place the firm foundation on which all subsequent beliefs could be grounded; it would guarantee that all subsequent claims based on it would be true. Descartes was big on doubting everything. For us to distinguish this base of ultimate truth and knowledge, of which all other knowledge can be based, Descartes described a process. This method is to take away all confidence in which has been taught, what the senses tell us, and what is thought is obvious, basically, regarding all that is known by us. !
             In order to determine whether there is anything we can know with certainty, he says that we first have to doubt everything. This doubting does not fully seem unreasonable. What he suggests is that, in order to see if there is some belief that cannot be doubted, we should temporarily believe that everything we know is questionable. Since sense experience is sometimes deceiving, it is obvious to Descartes that there are two operative ways of which to draw knowledge. They are intuition (A*B B*C) and deduction (A*C). Anything else cannot be the basis for claims of knowledge. We cannot know that what we experience through the senses is true with any certainty. So the best thing to do is to doubt our senses. Furthermore, we cannot be sure that we really exist, have bodies, or that experience of the world in general can be trusted. After all, we could be dreaming the entire thing. Next, we cannot even be sure that mathematical propositions such as 2+2=4 or that tri...