## Question about Cogito, ergo sum

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As far as I know Decartes tried to prove that he existed from the fact that he was thinking. And he thought this was only proof. My question is following:

-- why is the argument brought up above, stronger, than argument like this for example, I can see sky, therefore I exist? If someone says because this is illusion and maybe you are in a dream. Then why can't it happen that in dream, I "think" that I think, but in reality I don't.

Not sure if I properly formulated my argument but I hope you get the idea what I am trying to say. Why is Decartes argument about thinking more powerful that if he used other things, like I feel pain, therefore I exist.

1It is not more powerful. If you feel pain, even if the pain is an illusion, something is performing the act of feeling nonetheless and must exist, and that something is you. – armand – 2021-02-08T17:04:27.337

@armand So why is that argument from decartes described in the literature, and not the one about pain from OP for example, if they have same strength? – None – 2021-02-08T17:13:20.583

2Descartes later clarified that cogito ergo sum was not meant as an argument, but rather a direct existence claim that he "could not bring himself" to doubt. The extra "power", if any, comes from self-referential nature of it: even if you are doubting that you are thinking you are still thinking to do the doubting. This won't work with the blue sky. – Conifold – 2021-02-08T18:47:59.817

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Does this answer your question? Could 'cogito ergo sum' possibly be false?

– Conifold – 2021-02-08T18:48:13.653

Does this answer your question? Can we say that "I Think Therefore I Am" was never about "I", or thinking, or "I" doing the thinking?

– Yuri Alexandrovich – 2021-02-09T07:48:06.503

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Welcome, don. Thanks for a nice, reflective question.

The cogito has much less importance for Descartes than is commonly supposed. Its significance is twofold: (1) it is (merely) the first truth which Descartes has come upon which (as he supposes) 'is necessarily true whenever it is put forward by me or conceived in my mind' (Med. II: Cottingham, II: 17). (2) Descartes realises that there is very little he can do with the cogito as an isolated truth. What he takes from it is that it is a 'clear and distinct idea' and that 'I now seem able to lay it down as a general rule that whatever I perceive very clearly and distinctly is true' (Med. III: Cottingham, II: 24). Med. III is packed with other ideas that Descartes incorporates into his argument on the ground that they are equally clear and distinct - e.g. 'there must be at least as much in the efficient and total cause as is in the effect', 'the objective being of an idea cannot be produced by potential being', &c.(Cottingham: 28. 32).

The cogito is also not self-standing. Descartes needs to make certain that clear and distinct ideas really are necessarily true. This leads him into what many take to be the 'Cartesian circle'. He proves that clear and distinct ideas are necessarily true by using clear and distinct ideas in order to prove the existence of a perfect God who is no deceiver and guarantees the truth of clear and distinct ideas. (This is a contested area but whatever the case about the Cartesian circle, Descartes very evidently does believe that he needs to secure the necessary truth of clear and dsitinct ideas. So even the cogito, whatever Descartes epistemological relief at its discovery, needs reinforcement.

That aside, and at the heart of your question, Descartes has no difficulty in accepting, 'I feel pain, therefore I exist'. In fact he accommodates just such a case in Med.III: 'But what then am I? A thing that thinks. What is that? A thing that doubts, understands, affirms, denies, is wiling, is unwilling, and also imagines and has sensory perceptions [et sentiens]' (Cottingham: 19). Among sensory perceptions are pains.

As for, **'Then why can't it happen that in dream, I "think" that I think, but in reality I don't', I suggest that we already have the answer to this. What would replace your 'I "think"' except 'I imagine' - I don't think but imagine that I do. But Descartes has already included imagination in thought, therefore in dreams I imagine = think that I think: so I think.

Reference

The Philosophical Writings of Descartes, II, ed. J. Cottingham et al., Cambridge: Cambridge University Press, 1984/ 2008.

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I don't think that Descartes:

tried to prove that he existed from the fact that he was thinking.

Rather, he tried to remove errors in his thinking by assuming a skeptical stance toward anything that he thought one might reasonably doubt. Then discovered for himself (although he likely read it beforehand) that he could not reasonably doubt his own existence, because the mere experience of doubting seemed to confirm his own existence.

why is the argument brought up above, stronger, than argument like this for example, I can see sky, therefore I exist?

Despite the phrase "cogito, ergo sum" (I think, therefore I am), Descartes did not see his awareness that he couldn't doubt his own existence as a syllogism, as a formal deductive argument based upon premises. Rather, his inability to seriously doubt his own existence was something of a psychological fact. I can doubt the existence of "the sky", and from a logical point of view it may be true that "I" must exist if it is true that "I doubt the existence of the sky". However, in doubting the existence of the sky, I may not be immediately aware of my own existence. My attention may be distracted by the appearance of the sky, and my knowledge that appearances may be illusions. However, when I turn my attention to the attempt to doubt my own existence, my mind immediately says "but wait! how can that be?"

So, from a purely logical deductive point of view, "I doubt the existence of X, therefore I am" may be a valid argument, from a psychological point of view, it is not as effective as the attempt to doubt my own existence.

At the risk of being redundant, I will answer your question

Why is Descartes argument about thinking more powerful that if he used other things, like I feel pain, therefore I exist.

If I am thinking about my pain, I may not be thinking about whether my own existence is something that I can reasonably doubt. My attention is on the pain, but not necessarily on the question "what may I reasonably have doubts about?"

To whomever downvoted my answer, could you explain your reasoning please? – Math Keeps Me Busy – 2021-02-10T01:34:54.437