Cogito, ergo sum though not explicitly as "cogito, ergo sum" in Meditation II: In 1644, Descartes published (in Latin) his "Principles of Philosophy" where the phrase "ego cogito, ergo sum" appears in Part 1, article 7: Descartes's margin note for the above paragraph is: Descartes, in a lesser-known posthumously published work dated as written ca. 1647 and titled ("The Search for Truth by Natural Light"), wrote: The proposition is sometimes given as . This fuller form was penned by the eloquent French literary critic, Antoine Léonard Thomas, in an award-winning 1765 essay in praise of Descartes, where it appeared as In English, this
Cogito, ergo sum and that "I" know what "thinking" is. He suggested a more appropriate phrase would be "it thinks" wherein the "it" could be an impersonal subject as in the sentence "It is raining." The Danish philosopher Søren Kierkegaard calls the phrase a tautology in his "Concluding Unscientific Postscript". He argues that the "cogito" already presupposes the existence of "I", and therefore concluding with existence is logically trivial. Kierkegaard's argument can be made clearer if one extracts the premise "I think" into the premises "'x' thinks" and "I am that 'x'", where "x" is used as a placeholder in order to disambiguate