The famous Cogito ergo sum opens with "I" can think, therefore "I" am. How does "I" establish "I" before "I" can "think"?

in other words how did "I" establish "I" before it could think in the first place

I believe that this was due to bad articulation even though the quote is still valid, it seems that Cogito ergo sum assumed his existence before his thoughts.

  • 1
    You need to clarify your question and ask something specific.
    – pichael
    Jun 16, 2012 at 6:29
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    If this confuses you, you really ought to read Descartes's Meditations, the work in which the Cogito appears. It's short, and understanding the context of the quote will clear up most (if not all) of your confusion. Jun 16, 2012 at 10:19
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    I couldn't figure out what the second sentence means. I thought I could, but then it dawned on me that I really am not entirely sure why you are confused, i.e., whether you are asking the common question of "why does thinking presuppose existence", vs. some strange problem you might have with starting with the premise "I think" (you seem to think that one is not allowed to do that). Needs some clarification there.
    – stoicfury
    Jun 16, 2012 at 16:28
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    As the others, I'm unsure I understand the question, but it might be related to the controversy about whether Descartes is warranted to use "I think" as a premise, as opposed to "There is thinking". The Wikipedia entry on the Cogito has a short discussion of this (in the Criticisms section, paragraph beginning "Perhaps a more relevant contention...")
    – Schiphol
    Jun 20, 2012 at 16:52
  • Possible duplicate, philosophy.stackexchange.com/questions/70/… Jun 22, 2012 at 12:35

4 Answers 4


1) I think.
2) (hidden premise) "I think" explicitly states there is an "I" doing the thinking; indeed, the very concept of thinking itself seems to require an existing thinker
3) I am/exist.

So either way, it's a trivial, forgone conclusion because it was implied in the very first premise. The real debate lies with whether thinking requires existence, or rather, what are the minimal conditions of existence that need be satisfied for thinking.

  • Maybe we could think "Something is thinking, therefore something exists", and, later, call this something "I". May 31, 2013 at 20:24
  • Yes, it invokes the same idea: we naturally find it quite difficult to conceive of things capable of thinking which themselves don't exist. :)
    – stoicfury
    Jun 1, 2013 at 0:21

The thought in question is articulated into language for our convenience, and language is sequential, with one thought appearing after with each other. Without language the entire thought is in itself a whole without parts, even if the translation into language shows a sequence which relies on logic that must be then in sequence. This prompts a question: is logic an artifact of language?


I think therefore I am

is not a theorem in a deductive logic system. Rather it is an inescapable conclusion for a thinking being. Either you acknowledge that you think and that you are, or you deny it. But if your denial is correct, then there is no you to deny it and/or your denial is done without thought.

This is the way I thought of this Cartesian meditation when we studied it in school.


It means that if you are thinking, then you exist. If I state or mention that I am, at the beginning of any statement, unless I am an AI generating statements then you can deduce that I exist. The origin and existence of the I, the entity or individual, is not a matter in this statement. Your question expresses: How does the thinker know to refer to himself as I? I don't think a caveman chose the word I, but I'm pretty sure there was a lot of finger-pointing and arguing before it was decided on who to refer to as You, I or Us. The quoted expression acknowledges the significance of his existence.

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