Cogito, ergo sum “I am thinking, therefore I exist” appears in the CSMK translation of Descartes's correspondence in French (“, ”) to colleagues at CSMK III 247. The earliest known translation as "I am thinking, therefore I am" is from 1872 by Charles Porterfield Krauth. As put compactly by Prof. Krauth (1872), "That cannot doubt which does not think, and that cannot think which does not exist. I doubt, I think, I exist." The phrase "cogito, ergo sum" is not used in Descartes's "Meditations on First Philosophy" but the term "the "cogito"" is used to refer to an argument from it. In the
Cogito, ergo sum distinctiveness of self-evident propositions — to establish true and justified propositions despite having adopted a method of generalized doubt. As a consequence of this demonstration, Descartes considers science and mathematics to be justified to the extent that their proposals are established on a similarly immediate clarity, distinctiveness, and self-evidence that presents itself to the mind. The originality of Descartes's thinking, therefore, is not so much in expressing the "cogito" — a feat accomplished by other predecessors, as we shall see — but on using the "cogito" as demonstrating the most fundamental epistemological principle, that science and mathematics are justified by