Descartes Epistemology - Essay Example

Both the rise of modern science and the rediscovery of skepticism were key influences on Descartes' epistemology (Stroll; Newman). Descartes considered the supposition that all of one's beliefs are false. But Descartes claimed that it is not possible for all of one's beliefs to be false, for anyone who has false beliefs is thinking and knows that he is thinking, and if the person is thinking, then that person exists (Garza). Also, it was obvious that nonexistent things cannot think. So, "Cogito, ergo sum", i.e., "I think; therefore, I am".

Descartes says: "I immediately realized that, though I wanted to think that everything was false, it was necessary that the "me" who was doing the thinking was something; and noticing that this truth - I think, therefore I am - was so certain and sure that all the wildest suppositions of skeptics could not shake it, I judged that I could unhesitatingly accept it as the first principle of the philosophy for which I was seeking." (Discourse on Method).If one could know only that one thinks and exists, human knowledge would be depressingly narrow (Stroll).

So, Descartes proceeded to broaden the limits of human knowledge. However, knowledge-based on authority is set aside because "even experts are sometimes wrong". Knowledge from the sensory experience was declared untrustworthy because "people sometimes mistake one thing for another". Knowledge-based on reasoning is rejected as unreliable because "one often makes mistakes". Finally, knowledge may be illusory because "it comes from dreams or insanity or from a demon able to deceive men by making them think that they are experiencing the real world when they are not" (Meditations).

Here, methodic doubt was Descartes' main principle, rejecting as though false all types of knowledge by which he was ever deceived. Literally: "it is necessary to demolish everything completely and start again right from the foundations" (Meditations). Descartes' method of doubting all that is uncertain, then one would be reduced to solipsism, the view that nothing exists but one's individual self and thoughts (Stroll). To escape this, Descartes argues that all ideas that are as clear and distinct as the cogito (i.e. thinking) must be true, for, if they were not, the cogito also could be doubted.

Since "I think, therefore I am" cannot be doubted for its obviousness, all clear and distinct ideas must be true. Here, Descartes concedes: "There may be reasons which are strong enough to compel us to doubt, even though these reasons are themselves doubtful, and hence are not to be retained later on." (Replies, cited after Newman).Finally, on the basis of "clear and distinct" innate ideas, Descartes establishes a variety of ideas, e.g. that each mind is a spiritual substance and each body a part of one material substance.

It is necessary to note that "proof" for the existence of God is at the heart of Descartes' rationalism (see Stroll and Newman), for it establishes certain knowledge about an existing thing solely on the basis of reasoning from innate ideas, with no help from sensory experience. For instance, Descartes argues the existence of the world by the somewhat subjective (and therefore, weak) idea: "because God is perfect, he does not deceive human beings". Thus Descartes claims to have given metaphysical foundations for the existence of his own mind, of God, and of the world.

These foundations are very weak now. However, rational and skeptic Descartes' approaches (and also the idea of equivalence of clearness and validity) were survived and used in the foundations of modern science, e.g. in mathematics and physics.