In Meditation on First Philosophy, Descartes argues many points from his existence to all the false beliefs and ideas he had accepted from childhood.

One of the first arguments he begins with is by bringing into doubt all the beliefs that comes to us from our senses. His aim in the arguments is not to prove that nothing exists or that it is impossible for us to know if anything exists, but to show that all our knowledge of these things comes through the senses and it is open to doubt. He uses three arguments to open all our knowledge to doubt. He says that the basic idea is that we don't ever see external objects directly but only through out minds, the images that external object produce in us. Since experiences that come through the sense do not allow us to interact or come into contact with the object itself. But only the mental

2. Origination of ideas: Locke says that knowledge comes from experience and that all our knowledge is build from ideas. He concludes from this that all of our knowledge can be accounted for by accounting for the origin of the ideas. Two sources of our ideas are sensation, which is when we turn our sense toward that world and receive information in the form of sight, sounds, smells, and touch. Through our senses we receives ideas such as sweet, loud, blue etc. Reflection is when we turn our mind on itself and receive ideas as thought, belief, doubt and will.

Descartes says that instead of assuming God is the source of our deception, he says to assume that there exists an evil demon that has the ability of deceiving us the same way God did. He reasons that he has a legitimate reason on why to doubt what the senses say entirely as well as mathematical knowledge.

2. Deceiving God: " And yet firmly rooted in my mind is the long standing opinion that there is an omnipotent God who made me the kind of creature that I am. How do I know that he had not brought it about that there is no earth, no sky, no extended thing, no shape, no size, no place, while at the same time ensuring that all these things appear to me to exist just as they do now? What is more, since I sometimes believe that others go astray in cases where they think they have the most perfect knowledge, may I not similarly go wrong every time I add two and three or count the sides of a square, or in some even simpler matter, if that is imaginable? But perhaps God would not have allowed me to be deceived in this way, since he is said to be supremely good. But if it were inconsistent with his goodness to have created me such that I am deceived all the time, it would seem equally foreign to his goodness to allow me to be deceived even occasionally; yet this last assertion cannot be made." (24)

Some topics in this essay:
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