Descartes establishes "doubt", of everything that cannot be absolutely ascertained to the thinker's immediate awareness, as a foundation for further philosophical research. He does this through the famous "Cogito" where a thinker's perception of his own thinking cannot be doubted by him. And here is the thing: It cannot be doubted even according to the most stringent set of sceptical criteria conceivable. "Cogito Ergo Sum" (I think therefore ... I exist/am) is the rock of knowledge, the ultimate undoubtable truth, "the only thing we really, really, really know". Note: Notice how in Latin the subject (I) and the verb (to be) are one ... making the meaning clearer that not even the "I" (as a separate "thing") is posited. You are aware that you are thinking, therefore even if everything is untrue, even if your perceptions are mistaken and everything you experience a dream, something (you) is thinking ... therefore ... something is ... namely, the thinking process that is aware of the thinking process ... something that you perceive as "I". There is nothing ... but you know that thinking occurs ... therefore something exists ... and suddenly ... you have yourself a universe! Wow! :) ( )

The Cartesian subject gets a bad wrap these days, but I'm down with "cogito, ergo sum" with a couple of (admittedly pretty major) modifications from psychoanalysis and poststructuralism.First, when I'm assuring myself of my own ego-existence by thinking, "I am thinking, therefore I am," that's all well and good. But sometimes I might slip and think something like, "I am winking, therefore I am" becuase I'm distracted by the memory of a cute girl that winked at me today--in other words, the smooth functioning of the internal monologue that assures "me" that "I" exist is constantly being interrupted by the unconscious. That's why we need to add insights from psychoanlysis to Descarte's subject.Second, the "I am" bit needs to undergo a critique of the metaphysics of presence based upon Derrida's discussions of signification and being. The auto-affecting interior monologue happens in language, and language works by difference and reference to a whole system that must have a ghostly presence-yet-abscence to function. So when I say "I am," I'm also referring to a whole system of signification which is not "present" in the way we usually mean. So, the being indicated by the "I am" of the Cartesian subject should be modified by poststructuralist critique so that we understand it as a kind of being that is not simply unified, proximate, and present-to-itself. That being is necessarily characterized by difference, dispersion, and deferral in time.On another note, the God proofs--a restatement of Anselm's ontological argument along with Descarte's own version--are intriguing but still don't cut it for me. Ultimately, I don't think reason can pull that off--I think it's revelation or nothing (in my view as an athiest-leaning agnostic the answer is, "nothing," but that's up for debate). ( )

Two of the seminal works in philosophy, these are the foundation of modern philosophy. Descartes clears the way with his self doubt, summarized in the famous dictum, "cogito ergo sum". Much thought proffered here and the base for many others, including Spinoza, Hobbes and Leibniz, to critique and dicuss. ( )

Descartes did some interesting things; it's a shame he also did such stupid ones. ( )