Rationalism senses. For instance, his famous dictum, "cogito ergo sum" or "I think, therefore I am", is a conclusion reached "a priori" i.e., prior to any kind of experience on the matter. The simple meaning is that doubting one's existence, in and of itself, proves that an "I" exists to do the thinking. In other words, doubting one's own doubting is absurd. This was, for Descartes, an irrefutable principle upon which to ground all forms of other knowledge. Descartes posited a metaphysical dualism, distinguishing between the substances of the human body (""res extensa"") and the mind or soul (""res cogitans""). This
Cogito, ergo sum Translation needs a larger context to determine aspect. Following John Lyons (1982), Vladimir Žegarac notes, "The temptation to use the simple present is said to arise from the lack of progressive forms in Latin and French, and from a misinterpretation of the meaning of "cogito" as habitual or generic." (Cf. gnomic aspect.) Ann Banfield writes (also following Lyons), "In order for the statement on which Descartes's argument depends to represent certain knowledge, … its tense must be a true present—in English, a progressive, … not as 'I think' but as 'I am thinking, in conformity with the general translation of