|Cogito: "I think". According to Descartes the prove that I exist, because the subject may even reach the doubts about its existence just by thinking and the subject must exist in order to think. Kant speaks of the "I think" that must accompany all my ideas/conceptions/notions/presentations, in order to make them my representations.See also thingking, existence, justification, representation.|
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Cogito/Descartes/Hintikka: the cogito is not a premise whose conclusion would be the sum.
Solution/Hintikka: it is an act of thinking that proves the existence of the subject itself.
Analogously: a speech act also proves the existence of itself to the subject. Mark Twain says: "I exist".
HintikkaVsDescartes: Problem: 1. What kind of entity is this, which should prove "res" with it?
2. To answer the question, what has been proved at all, we need to clarify the status of the entity.
E.g. Italo Calvino: Charlemagne asks a knight why he has closed the visor. He answers; "Sir, I do not exist".
Existence/non-existence/subsistence/Hintikka: in this example, the knight does not exist in a certain way, but in another, namely, in which he can be the hero of history.
N.B.: i.e. here the speech act is not a conclusive proof of its existence. ((s) Within fiction).
Cogito/Descartes/Hintikka: it would have been wrong, too, had Descartes concluded:
"Cogito, ergo Descartes exists". ((a) So for the "I", which is explicit in "sum", insert the name).
Analog: For example, if someone tells me in the street: "Mark Twain exists" that would be just as little evidence for the existence of Mark Twain. It would have to be him who performs the speech act.
Cogito/knowledge/Hintikka: Problem: Descartes must also know additionally that the questionable thinker is this entity, or that type of entity.
Existence/Identity/Entity/Identification/Quine/Hintikka: Quine: "No entity without identity": that is, Descartes needs to know something about himself to be able to say about himself that he exists.
Solution/Hintikka: we must distinguish two types of cross-world identification (cross-identification).
a) perspective (subject-centric) identification: this is not subjective, even if it is relative to a person.
It only uses one coordinate system defined by reference to the user. It itself depends on objective general principles.
b) public (object-centered) identification.
Jaakko and Merrill B. Hintikka
The Logic of Epistemology and the Epistemology of Logic Dordrecht 1989
J. Hintikka/M. B. Hintikka
Untersuchungen zu Wittgenstein Frankfurt 1996