Is the opposite of Descartes dictum “I think therefore I am “ also true ?

That is ,

Is “I am unable to think therefore I am not” also true ?

That is ,

Can I say “Those unable to think do not have Self” ?

  • Thank you for the question. It woud be interestingif that were true.
    – Hudjefa
    Commented Oct 28, 2023 at 8:47
  • If you are placed under anaesthesia you are unable to think- does that mean you don't exist while in that condition? Commented Oct 28, 2023 at 8:58
  • 3
    No, being does not require thinking. Moreover, cogito does not work in the third person, and in the first person your opposite does not work. Those who do not think cannot think of that either.
    – Conifold
    Commented Oct 28, 2023 at 8:59
  • but then, maybe it does. anyway, C implies S does not mean S implies C. he was a dualist, descartes, though that's about all i know
    – user67675
    Commented Oct 28, 2023 at 15:44

2 Answers 2


OP: Is “I am unable to think therefore I am not” also true ?

This depends on the understanding of 'am'... being, of which there are different levels. The existence of an object in nature is different from the experience of existing. Regarding the existence of objects, Kant says 'existence' is not a predicate but is the relation of an object to consciousness, e.g. Critique of Pure Reason A598/B626

... the determination of a conception is a predicate, which adds to and enlarges the conception. It must not, therefore, be contained in the conception.

Being is evidently not a real predicate, that is, a conception of something which is added to the conception of some other thing. It is merely the positing of a thing, or of certain determinations in it. Logically, it is merely the copula of a judgement.

From this point of view, if you are unconscious no judgements are being made and no existence is formed. (Although another person may see you.)

In the more mysterious, higher order of existence that Descartes would probably wish to mean, you exist whether awake, asleep or unconscious, as a self which can generate consciousness from unconsciousness.

Therefore the answer to the OP's question is "true and false" depending on the type of existence.


Is the opposite of Descartes "Cogito ergo sum“ also true?

The example offered in the post is not true.

The example negates the antecedent ("I think"), which does nothing logically. If the consequent ("therefore…") were the only thing negated, then that would make a difference.

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