Epistemology is the philosophical study of knowledge. There are two distinct main ideas that branch off epistemology, rationalism and empiricism. Rationalism is acquired independently or prior to sense experience. One of the main rationalist is Rene Descartes who was a very influential philosopher who had a problem of knowledge and how to justify it. He believed that humans contain innate ideas. Empiricism is also known as a posteriori, it depends entirely on the sense perception. The leading empiricist is John Locke and he rejects the concept of innate ideas.There are also other empiricists that support Lockes concept such as George Berkeley and David Hume. Nevertheless, this criticism of Locke to Descartes, prove more than enough, that the empiricist account is more plausible. .
In Descartes first Meditation he focused about doubt and innate ideas. The Meditation texts describes the concept that since our senses are fallible, it is prone to error and cannot be trusted and our mind is the only knowledge that remains. He continues to say that we are in a dream state where our senses are deceived and it doesnt correspond to the world. One cannot distinguish dreaming from reality if theyre depending on their senses. Descartes proceeds to talk about an evil genius/demon deceiving the senses and manipulating all the experiences (Descartes p.200). He is skeptical about the knowledge that derives from the senses and you cant know anything based on experience. .
Descartes believes that knowledge is built up with a strong foundation. It is beliefs based on other beliefs, but on the bottom is a firm foundation of belief. It doesnt appeal to the senses and the use of pure reason to get knowledge is a necessity. The Cogito Argument provides the foundation for knowledge, I think, therefore I am (Descartes p.202).The Cogito is the first instance of a truth that cannot be doubted .When he speaks about I" he is referring to the mind, when you think, there is thoughts therefore you exist.