I am thinking, of this I am sure

During the seventeenth and eighteenth centuries western philosophy was divided between British Empiricists and Continental Rationalists. Both of these theories concern epistemology, which the theory of where knowledge derives from. Empiricists, such as Locke, argue that all of your knowledge is derived from sensory experience. However Rationalists, such as Descartes, argue that pure reason and the mind alone, is the source of knowledge.

Cogito Ergo Sum - I think therefore I am; a pretty standard thought. This however is one of the fundamental principles of Rene Descartes’ philosophical theories. Descartes was around during the seventeenth century and was a contemporary of Galileo. He shared similar views to those held by Galileo and Bacon, and was opposed to Aristotelians and the traditional education that was available in universities at the time. Descartes embarked on a life in action, in the hope that this would give him insight as he then went on to search for ‘true knowledge’. One of his main theories is the concept of ‘Cartesian Doubt’, which is that you can only be certain of what is in your own mind; everything else could have been put there by a demonic imp. According to Descartes you should doubt everything, except God and your own existence. Unlike Plato, who argued that there was a realm of the forms, Cartesian philosophy contains three realms: mind/soul, matter and God. Mind and matter are both created substances whereas God is an uncreated substance. Descartes argued that God is the supremely perfect being, which you gain the idea of through a conglomeration of your sensory experiences.