Cogito, ergo sum is "Since I doubt, I think; since I think, I exist"; with rearrangement and compaction, "I doubt, therefore I think, therefore I am", or in Latin, "dubito, ergo cogito, ergo sum". A further expansion, ("…—a thinking thing") extends the "cogito" with Descartes's statement in the subsequent Meditation, , or, in English, "I am a thinking (conscious) thing, that is, a being who doubts, affirms, denies, knows a few objects, and is ignorant of many …". This has been referred to as "the expanded "cogito"". Neither nor indicate whether the verb form corresponds to the English simple present or progressive aspect.
Cogito, ergo sum the "I" from the thinking thing. Here, the "cogito" has already assumed the "I"'s existence as that which thinks. For Kierkegaard, Descartes is merely "developing the content of a concept", namely that the "I", which already exists, thinks. As Kierkegaard argues, the proper logical flow of argument is that existence is already assumed or presupposed in order for thinking to occur, not that existence is concluded from that thinking. Bernard Williams claims that what we are dealing with when we talk of thought, or when we say "I am thinking," is something conceivable from a third-person perspective; namely objective "thought-events"