The other day I came across a blog entitled "cogito, ergo sum" (Latin for: I think, therefore I am). It had the caption "girls think, therefore I am" printed underneath it. It was not the first time I had seen this phrase of Rene Descartes' (1596 - 1650) misunderstood and misused in this manner. This brief tract is an attempt at explaining this canonical philosophical principle.
Rene Descartes was a French mathematician, philosopher and scientist- who set out to discover the "Archimedean point" of knowledge. The concept of the Archimedean point comes from Archimedes' own proclamation: “Give me a place to stand and with a lever I will move the whole world.” So in this way, Descartes was searching for the epicenter of knowledge- making Descartes an epistemologist: a philosopher concerned with essential theories of knowledge.
Descartes begins his journey as an epistemologist with "methodic doubt": rejecting as false, all sorts of knowledge by which he was once deceived. The first thing to go was knowledge based on authority, because even experts are sometimes wrong. Second to go was knowledge based on sensory experiences, because people can perceive one thing as another, like in the case of mirages. Third to go is knowledge based on reason, because this too can be wrong, as in the case of calculation. But the fourth and final aspect driving Descartes' skeptic doubt is what he described as the "evil demon" that is capable of creating an illusory world for people which does not exist- making them believe and see that, which is not. "Cartesian (Descartes') doubt" is an odd skepticism in this sense. It is a rational approach towards validating one's own existence, as well as the existence of a God.
After doubting even the existence of the nose on his face or basically anything at all, Descartes found himself facing one of the greatest of quagmires: how can I know that I exist? This "doubt" of his that engulfed him was to reveal to him the answer to this problem. Since his search for something that can no longer be doubted, required him to doubt everything- then the very act of doubting was the evidence of "thinking" that was indubitable- and since he was the person who was thinking, he too must exist. Thus, Descartes says: I think, therefore I am.
This powerful maxim has since ignited the argument for mind-body duality in psychology. In other words, Descartes' statement has given weight to the belief that "mind" and "body" are separate.