Strictly speaking, "Cogito ergo sum" simply means:

  1. "The existence of your own mind can never be in doubt."
  2. Item 1) also describes our true knowledge in its entirety.

Or we can say that strictly speaking, beyond our own mind's existence, nothing can be known. Ever.


The above sounds simple enough (if suicidal1). Yet one look at the "similar questions" tab to the right is enough to see how confusing these three Latin words remain to this day. What makes Descatres's proposal so uniquely cryptic is that its central premise was actually formulated in the context. Let's recall where Descartes was going with this.

He opens the First Meditation asserting the need “to demolish everything completely and start again right from the foundations” (AT 7:17, CSM 2:12).

The question he was trying answer, therefore, was "What, if anything, we can know for sure, without any possibility of doubts?"

The argument notes that some of our perceptions are inaccurate. Our senses can trick us; we sometimes mistake a dream for a waking experience, and it is possible that an evil demon is systematically deceiving us we live in a simulation. That alone is enough to conclude that nothing we perceive as real, actually is so.

The perception itself, however, is happening (consumed?). Which necessitates the existence of our mind consuming the perception. Descartes asserts that much:
"So after considering everything very thoroughly, I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind." (AT 7:25, CSM 2:16f).

Notice that Descartes didn't bother to mention the thought process in that first formulation of his proposal because it was always about the existence of the mind being necessary, even if the said mind were lacking consciousnesses (the "I" or Self) and, thus, the capacity to think for it-Self.

Such a mind would still have at least the sensory and emotional experiences (and it would probably experience thoughts in some form, though not of its own). That perception would still exist for real, making it necessary for the mind consuming it to exist for real.


To sum up, there are two distinct concepts that "I" refers to:

  1. the conscious/rational Self of "I think"
  2. the subject of perception

Descartes himself failed to make that distinction, and the rest is history.


So the first question: Does the above suggest that "Cogito Ergo Sum", is, indeed, neither about "I" nor "thinking"?"

And if yes, it would be only logical to ask..

The second question: Why would Descartes bring "I think" in his proposal, creating such a widespread confusion? -- I'm going to suggest the answer below.


1 Being entrapped in your own mind, with no way of knowing anything beyond that -- it does sound rather disheartening, I'm not gonna lie. But that is not how the story ends. There is a constructive way out, even tho discussing it lies beyond the scope of this question.


  • I'd agree about the I, but what is there to the "mind" for Descartes if not the thinking?
    – Conifold
    Commented Jun 23, 2020 at 20:21
  • I think the mind in your question refers to his "I", the conscious/rational Self. The latter -- aside from, yes, thinking (often but not always) -- would be consuming perceptions almost 24/7. Non-stop when awake, and dreaming when asleep. Commented Jun 23, 2020 at 22:25
  • And, again, the above might not describe what most people experience. Commented Jun 23, 2020 at 22:26
  • 1
    The usual fix to cogito is "thinking is occurring, therefore something is". The I is out, but if the point is the existence of the "mind" then this mind is just another label for the "thinking". The rest it might be, like perceiving, is suspect along with perceptions. Of course, truth be told, the same applies to the "thinking", as we can be deceived about any characteristic that distinguishes it from something else, and it all reduces to "something is occurring and so is". Then it isn't even about the mind, but Descartes isn't really known for seeing things through.
    – Conifold
    Commented Jun 23, 2020 at 23:13
  • 1
    Does this answer your question? Is 'cogito ergo sum' an example of begging the question? Commented Jun 24, 2020 at 5:07

2 Answers 2


In my opinion it must be about the "I" and the point is important today.

Some think that the universe and/or our minds are computer programs or computations running in some kind of cosmic computer, or a simulator. Or an evil daemon as Descartes would have said.

But even if this is true; even if we're just programs in some cosmic computer, or an "ancestor simulation" as Bostrom speculates; we still have our I. And simulation theory does not have an explanation for the I.

On the other hand, perhaps the I is also a product of the simulation; in which the simulation theorists owe us an explanation of exactly how the trick of implementing self-awareness is accomplished.

After all I could simulate my ancestors in a computer, but they would not be self-aware any more than my Web browser is.

The question of the I is vital. Even if I'm a brain in a vat, I am still an I. And the vat doesn't explain the I. This point is frequently overlooked by the simulation advocates.

  • There is not one, but two very distinct concepts of "I" in this thread. One is the conscious/rational Self of "I think". The other refers to one's mind as a whole, like in "The existence of your own mind can never be in doubt." <== your "I" is the second kind. I too argue that "Cogito ergo sum" is should be about the mind in general, NOT about the conscious Self. Descartes failed to make that distinction because he himself was the conscious Self and, he thought, so is everyone else. Commented Jun 25, 2020 at 19:32

why would Descartes bring "I think" in "Cogito ergo sum"?

The reason Descartes didn't see the controversy, is that "I think" was an accurate description of how the mind works in some people. Descartes would not experience "thoughts", there would be no automatic thought process for him.
Rather, the thinking was a conscious effort on his part, like walking. For him "I think therefore I am" semantically similar to "I walk, therefore I am awake".

And another Descartes quote stating the point above:

Except for our own thoughts, there is nothing absolutely in our power.”
   ― René Descartes

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