Since ancient Greek and Roman philosophy, there have immerged a good number of thinkers who have been in trouble with epistemological problems. Pre-Socratic thinkers were mainly dealing with cosmological questions; the origin of the universe. The question of epistemology started by sophists who tried to speculate whether human mind can know things as they are or not.

The discussion went on through many centuries up to modern era, where Descartes is seen as the main character, who held a discussion in rationalistic school of thought. He wanted to boast himself of finding the truth from where the whole philosophy finds its ground. Moreover, in methodical doubt, he shows how rationality provides the answer of everything, such as the knowledge of God, triangle, trigonometry and many of the like with exception of sense experience.

Descartes rejects all sources of knowledge, which grounds from sense experience, tradition and religion. But when we look carefully, we will discover that, though he doubted on them, still was sure that not all of them were false. That is why his doubt was termed methodical, meaning doubting for the sake of knowing, unlike skeptics who end up with despair.

In this treatment of methodical doubt, I aimed at exploring his knowledge, researching to whether his method is absolute in so far as knowledge is concerned. ‘Cogito Ergo Sum’ I think therefore I am, is his summation of his knowledge after weighing between man and God and other living creatures, which one can think critically? He came with his answer that in God we can’t criticize his existence and thinking, for from him we are able to think. Man as an ideal thing, a thinking thing is aware of present, past and the future. Man cannot accept everything for granted, he doubts and after doubt he affirm or negate.