Could Descartes' assertion that it's self-evident that a "self" exists be seen as an example of begging the question, because in his attempt to understand existence, he seems to define it as, in part, "something that can think"?

  • I am no spinozist and hopefully someone like @CharlesMSaunders will step in to "improve my understanding" As I know: In "improvement of understanding" Spinoza makes the distinction between true and fictitious scepticism. And classified Descartes in the latter.
    – Rushi
    Nov 14, 2019 at 4:21
  • "I think" is the premise. "I am" is the consequent. There's no begging the question. If he doesn't exist, then he also doesn't think, which is absurd.
    – user18800
    Nov 14, 2019 at 5:42
  • It is debated if the Cogito is correctly interpreted as an inference; it may be raed as an intuition : "I must finally conclude that this proposition, I am, I exist, is necessarily true". In this case : no argument there, and thus no fallacy. Nov 14, 2019 at 7:27
  • 1
    That "existence" of something follows from it performing an action, in this case thinking, is part of the colloquial convention for using the word. Descartes would be begging the question if he redefined common usage, not followed it. That he attaches "I" to the observed thinking is often criticized as a non-sequitur, see Could 'cogito ergo sum' possibly be false?, but once that is done existence of that same "I" follows unproblematically.
    – Conifold
    Nov 14, 2019 at 8:47

5 Answers 5


Descartes recognized this himself. In the book Philosophy East/Philosophy West: A Critical Comparison of Indian, Chinese, Islamic, and European Philosophy, One of the authors, Ben-Ami Scharfstein writes in chapter 5 (p 201-2):

It is perhaps surprising that in Descartes' own writings, the Latin formula, 'Cogito ergo sum', does not appear. The Latin translation of the Discourse says, 'Ego cogito, ergo sum, sive existo', while the Latin in the Meditations is, 'Ego cogito, ergo sum'. In both Latin formulas, there is an emphasis , which fits Descartes own exposition, on the I, the dramatic implication being that this is an argument to be used by the very person who has been trying, unsuccessfully, to doubt his own existence. In view of what has earlier been said on the verb to be, it is interesting to note that in the first of the Latin formulas, the verb sum is apparently not enough to convey the necessary stress on existence, so a second, less equivocal verb, existo, is added to strengthen it. [author's footnote: On the addition of existo, see Gilson, Discourse, p 292]

Descartes temporary omission of the 'therefore' from his argument was the result of his fear that he would be vulnerable to the charge that the argument was nothing more than the conclusion of the syllogism: 'All that thinks exist. I think. Therefore I exist.' It would clearly be awkward if the first of all reliable truths were only the conclusion of a syllogism. Questioned on this point, Descartes answered:

"When one becomes aware that we are thinking beings, this is a primitive act of knowledge derived from no syllogistic reasoning. He who says, 'I think, hence I am, or exist', does not deduce existence from thought by a syllogism, but by a simple act of mental vision, recognizes it as if it were syllogistically deduced, the major premise, that everything that thinks is, or exists, would have been known previously; but yet that has rather been learned from the experience of the individual--that unless he exists he cannot learn. For our mind is so constituted by nature that general propositions are formed out of knowledge of particulars." [author's footnote: 'Reply to Objections II', 'Thirdly': Haldane and Ross, vol. 2, p 38.]

It might be better to say something that is 'aware', as 'aware' implies existence.

  • I like the historical note. But the Cogito is one of the most widely recognized arguments in the English speaking world, regardless if Descartes wrote it as it is commonly translated. The post quotes a source but does not answer the OP, which asked if the Cogito is guilty of begging the question.
    – Rob
    Nov 19, 2019 at 17:50
  • I do apologize: I apparently voted down on this answer. That was a mistake. But the site won't let me remove my down vote. Sorry!
    – Rob
    Nov 19, 2019 at 17:55

Yes, it is from an eastern point of view.

In some eastern philosophies such us Buddhism and Samkhya (old Hindu philosophy school). Ego( "I" ) mind ("think") and consciousness(thoughtless silent observer of the mind) are clearly separated as different entities. See Tattvas ref here

Descartes is using the mind or circular reasoning to determine his own existence. That is to say he needs a mind, a thought or doubt to know he exists. eg. Doubting the doubter or watching the observer in you.

Advanced types of meditation are about creating thoughtless states of consciosness to experience a deeper understanding of existence.

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    While I upvoted this, I think your last para should be "...creating thoughtless states of consciousness..." That is after all the point of your post isn't it? That post Cartesian westernity equates thought and consciousness
    – Rushi
    Nov 20, 2019 at 15:22

My take on it: assume (for reductio) that you don't exist. Then you infer that you don't doubt that you exist, since you don't exist to doubt (or do anything at all). But since you can never infer that you doubt your existence (as such), it follows that in being able to doubt, you must know that you exist: in other words, "If I didn't exist, I would not doubt; I do doubt; therefore, I exist."

  • what if "thinking," or "doubting," is really just an observed experience with no real free will, and what we experience to be thoughts are simply the bi-product of some pre-destined fate? in that case, how would this hold up to a "deceiving god"? not that I believe this to be true, but given the rigorous amount of doubt on other areas it seems odd to just stop there.
    – theupandup
    Nov 18, 2019 at 6:11
  • I think our ability to question any specific example of cause or effect, as well as our ability to question the law of causality itself, suggest that if we have free will, in the strong sense, it must come from our ability to ask questions in general. Nov 18, 2019 at 15:28

I once heard a philosophy professor say that Descrates' Cogito isn't properly an argument because an argument needs two premises and a conclusion.

And that is true of syllogistic logic, but it's not true in modern logics. In natural logic, for example, an argument is defined as "a set of premises, an inference marker, and a conclusion " and the logician Neil Tennant actually uses the Cogito as an example of an argument in his book 'Natural Logic' (Natural Logic, p.2)

I mention this to suggest that we are justified in treating the Cogito as an argument and thus analyzing it to see what, if any, fallacies Descartes committed.

Let C= I think 
Let E = I am

The *Cogito* can thus be expressed as the material conditional: C->E

But a material conditional doesn't prove anything, it's a statement not an argument, whereas the Cogito is an argument, not a statement. Fortunately we can convert the material conditional into the following argument:

enter image description here

However, this is invalid. There is no rule of inference in any logic that allows you to infer line 2 from line 1. And a truth-table would make clear that a truth-value assignment is possible where C is true and E is false. Thus the argument is invalid, and in this sense the Cogito is guilty of a non-sequitur.

To 'save' this argument, we need a second assumption, such as: "I think."

As an argument this can be expressed as:

enter image description here

This is a valid argument, that takes the form of modus ponens. Since Descartes (presumably) thought he had created a valid argument, we can infer that he implicitly assumed line 2. So, in that sense, yes he is begging the question.

In summary: yes, you can make the case that he is begging the question, but you can also make the case that he committed a non-sequitur, but regardless, the argument is invalid.

  • this gives good context, thank you
    – theupandup
    Nov 19, 2019 at 18:08
  • tangential question, but may I ask what tool you're using? I'm a computer scientist and this looks like it could be useful for some quick checking in proofs.
    – theupandup
    Nov 19, 2019 at 18:41
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    @theupandup: thanks! I'm glad you found it useful. The tool I used to generate and check my arguments is a web based application that you can find at proofs.openlogicproject.org. I find their notation for ~I and ~E to be a bit unusual, but the documentation is adequate. Good luck.
    – Rob
    Nov 20, 2019 at 0:24

The important aspect of cogito is the ending, it is not 'thinking exists, therefore I am', it is 'I think'.

I am not even sure you can get from 'thinking exists' to 'there is a thinker'. You can take an all-out Berkeleyan direction and imagine that thought is just a holistic independent process from which all apparent reality proceeds equally, undivided.

But we could not develop a language with a first-person ending unless 'first-persons' exist. (Ayn Rand's worst fears, notwithstanding.) The self cannot escape itself. When I am not sure anything else exists, there is still an I being unsure.

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