Descartes is recognized as “the Father of Modern Philosophy.” This epithet is due to his leaving behind medieval thinking and taking the methodology of the sciences to establish a rational foundation for truth. It is also the case because Descartes doesn't quote other thinkers but is doing philosophy on his own. This is evident from his beginning statements with phrases like “It seems to me that …” or “I am convinced that …”; it all adds up to an image of the solitary thinker.

In general, rationalism is a philosophic approach that emphasizes reason as the primary source of knowledge. Unlike Hobbes and other empiricists to come who thought that knowledge began with sense perceptions, Descartes thought that knowledge was prior to and independent of sense perceptions. In fact, truth is not tested by sense-verification procedures.