Descartes ignored all he believed to be true. He believed that if any belief can be doubted it is not certain, making it unusable as a foundation. Descartes jettisons any information, knowledge, or truths that are based on his senses. He applied the "Dream Argument," (19) where he stated that based on the senses alone, there is no definite way of proving that you are dreaming or awake. Therefore, any truths based upon the senses are unreliable and doubtful. Descartes turned to why and how his senses were deceivable.
Descartes spent Meditation One attempting to disprove his fundamental beliefs. First, Descartes doubts that he is able to trust his senses because they are occasionally wrong. An example of this is a longed haired person that may look like a woman from a distance, but as you get closer you realize that it is really a man. The dream argument dealt with telling if one is asleep or awake. According to Descartes, there is no way for one to tell whether he or she is awake or not. We decide what is real and what we can sense. The problem is that your brain can trick your senses. What you believe is there may not in reality really be there. Dreams can many times feel quite realistic in nature. Since one cannot trust his or her senses, one can conclude that there is no way to determine whether he or she is awake or asleep. However, he admitted that there were certain "truths" that were consistent with whether he was awake or asleep. Mathematics and logic are ideas that hold true regardless of the situation For example, two plus three equals five and a square has four equal sides. These beliefs remained constant in all states of living.
In regard to dreams, Descartes spoke of what he called the "Evil Demon". His "Evil Demon" argument was that one is being tricked by an outside source. This outside source has the ability to control all of one's senses. One has no power at all to stop this evil demon from putting ideas into your head. If the evil demon can control all of one's senses, nothing one senses or believes is present. Due to this, is it possible that a person has not done anything? What are you truly doing? There is a possibility that I dreamed writing this entire paper. My senses told me that I physically typed this paper. Was this all a dream? There were various background noises that distracted me while I was compiling this paper. Did I actually hear those noises? Descartes' thinking is complex and really makes a person think of whether they dreamt or actually experienced a particular event.
Descartes disproved these beliefs by abandoning the idea of a supremely good God. He had believed in god all his life. He brought up the argument of a different kind of God. This God's sole purpose was to deceive Descartes. Descartes' argument for the existence of God is then: if God is all perfection, existence is perfection. Therefore, God exists. Despite his many efforts to remove all imprecise information from his thoughts, Descartes' proves that God has some shortcomings, which have been pointed out over time. One problem was his idea of God. In order to see where the inconsistency lies, we must refer to his understanding of certainty and ideas, mainly methodic doubt. Ideas are concepts that resemble things outside of ones self. Using Descartes' own logic one can see that these ideas can be doubted. Why was God not doubted? Descartes formed an idea of God as an infinitely good being. He had to discover this idea within his own mind. According to his principle of universal doubt, he cannot simply know whether his conception of God is correct or incorrect. In other words, this idea was considered false until proven otherwise. Since, the idea of God is in doubt, the trustworthiness of one's reasoning must also be in doubt. Another problem with his proof was that he used his powers of reason without first proving that they were beyond doubt.
God's infinite perfection was made certain to Descartes through the very same capacities that he has not proven trustworthy. Descartes didn't trust his senses, yet he believed God existed through his senses. Descartes accepted the reliability of his ability in proving the existence and infinite perfection of God. This does not make sense. A doubtful ability would cause a doubtful argument, and in turn, produce a doubtful conclusion. But seeing how these ideas seem to be preconceived in his mind, even before he begins to doubt. Can they be preserved and used in his arguments? Even if they are logical, they must be doubted under Descartes own methodic doubt structure. Without them, he cannot prove the existence of God. Descartes is satisfied that he has adequately disproved the previous argument. Since he has done this he is now ready to lay down a new foundation of knowledge and find the "truth." This passage reminds me of the movie "The Matrix", in that God acts as the computers did in the Matrix. Descartes is trying to free his mind as Neo had to do because the computers only they let Neo see what they wanted him to by altering his senses, just like Descartes believes God is doing to him.
I feel that his argument is weak. Descartes claimed that in order to find the real truth he must not trust anything that he was taught or knows because his senses deceived him. Let us assume that our senses do deceive us. Is there really is a big, all-powerful, evil genius of a God? It would be impossible to ever find out the truth. Our senses deceive us. Everything we see, taste, smell, hear, and feel might be false. If this were the case, it would be impossible to ever find the "truth" because every piece of information and every belief, thought, and emotion comes from one of our senses. If God were all-powerful and deceiving there would be absolutely nothing we could to obtain the truth. Something that is all-powerful has control over every thought, belief, and idea that we have. If Descartes believed this then he must believe that this deceiving God was putting the idea in his brain that if he ignores his senses he will obtain truth. If his God was deceiving and all-powerful then he will never discover truth. Descartes tries an alternative way to look at reality, the initial idea and the concept as a whole. Descartes constantly contradicted himself in his explanation and his points seem to work against themselves, as opposed to supporting his hypothesis. At the end of the First Meditation the one thing that remained certain is that we all have the same perception, but existence is our own perception. Nothing in the external world is certain. Descartes could not think outside of the "box".
Descartes is a very wordy self-examining style of writing. It is often difficult to understand, and the concepts that he is trying to explain could be stated in a clearer and more coherent matter. His arguments were good, but they were written in a circular argument. It would have been much easier to understand if he hadn't written in circles and if he didn't contradict himself.

Descartes 8.6 of 10 on the basis of 3724 Review.