Cogito Ergo Sum

“I think, therefore I am” is the popularized formulation of Descartes’ famous cogito ergo sum (hereafter, “ cogito ”). The cogito 's epistemological significance is supposed to derive from its status as an utterly self-evident truth – “the first and most certain of all to occur to anyone who philosophizes in an orderly way” (AT VIIIA 7, CSM I 195). “Orderly” philosophizing involves a program of methodic doubt – doubt resistance, or indubitability , being the central criterion of knowledge . Some texts express the cogito 's underlying point in terms of doubt (itself a form of thinking): “It is not possible for us to doubt that we exist while we are doubting; and this is the first thing we come to know” (AT VIIIA 6f, CSM I 194). Barry Stroud (2010, 518) remarks that the cogito “is certainly among the most important and longest-lasting ingredients of Descartes's legacy.” Though Descartes’ treatment of the cogito is history's most famous, it is arguably not the first. Augustine of Hippo presented a remarkably similar version of his own: “If I am mistaken, I exist” ( Si fallor, sum ). The differences in formulation are not insignificant. Lively debates persist concerning Descartes’ own formulation. The most serious debate about formulation concerns inference . Versions of the cogito appear in each of Descartes’ three main published philosophical works. The “canonical” formulation (as I shall call it) includes an explicit inference – “I am thinking, therefore [ ergo ] I exist.” This version appears in two of the works: the Discourse (1637) ( je pense, donc je suis ), and the Principles (1644) ( ego cogito, ergo sum ). However, Descartes’ masterpiece, the Meditations (1641), presents a rather different formulation. The formula there occurs early in the Second Meditation in the context of an effort to find an indubitable truth: “So after considering everything very thoroughly, I must finally conclude that this proposition, I am , I exist [ Ego sum, ego existo ], is necessarily true whenever it is put forward by me or conceived in my mind ” (AT VII 25, CSM II 17). Which of these represents Descartes’ official formulation? What follows are three main interpretive options. One option is a noninferential interpretation. The most influential account comes from Jaakko Hintikka, who argues that the cogito should be understood as a performative utterance.