ABSTRACT
For centuries and up to this very day René Descartes has been regarded as the founder of modern Enlightenment philosophy, introducing a radical turn in Western philosophical and scientific thought. With the way prepared by thinkers of the Renaissance, Descartes broke definitively with the scholastic tradition of the Middle Ages since he turned against the doctrines of Aristotle, especially the doctrine about the senses being the one and only source of knowledge. Drawing upon the skeptical tradition of ancient Greek philosophy, which was revitalized in the Renaissance, Descartes in his philosophical writings, most explicitly in his Meditations on First Philosophy (1641), developed a two-part strategy, rejecting at the same time Aristotelian sensualism and skepticism. The key concept in this context is the famous notion of “methodological doubt.” This method has a double structure: first the sensualist theory is undermined by means of skeptical arguments (the so-called “argument of illusion” the “dream argument” and “the argument of an evil demon”), and thereafter skepticism is turned against itself. The result of this operation is the foundation of a radically new metaphysics. The “methodological doubt” involves both a destructive and a constructive part since the whole process terminates in a new doctrine of metaphysical thinking: the famous “cogito ergo sum.” Doubt and skepticism cannot be universal since I cannot possibly doubt my existence: for if I do not exist, I cannot doubt anything whatsoever. This is the point where skepticism contradicts itself and a new paradigm of knowledge emerges. Raised above any kind of doubt, as absolute certainty, self-consciousness or the “cogito” becomes the new standard of knowledge. All knowledge that is to count as genuine must fulfill the conditions of self-consciousness’ self-evidence and complete transparency. In order to secure the absolute validity and objectivity of thought and knowledge, Descartes reintroduces the “argument of the evil demon” or the “deceiving God,” by means of which he leads up to his epistemological version of the proof of God. So the source of knowledge lies within human reason, and God guarantees its ultimate validity. According to Descartes, this whole procedure is a purely rational enterprise that takes place within reason alone. The skeptical route leading to the absolute certainty
preconditions other than those posed by reason itself. By stressing the absence of any kind of precondition, Descartes formulates the very principle of what came to be known as modern Enlightenment rationalism.
