i am i exist
Philosophically, Descartes was concerned with the existence of reality.
Descartes found it impossible to doubt his own existence. The reason for this was that he felt that thoughts had to come from himself.
Short answer: Descartes' doubt was like WWI - the doubt to end all doubt. Only by doubting everything could Descartes hope to find anything that was certain (even if the only certainty is that nothing else is certain!).
For Descartes, this was the fact that he existed as a thinker. He was perfectly sure he was thinking; and he was likewise convinced that to be thinking he had to exist as some kind of substance.
i am i exist
Descartes believed that the truth must be indubitable because doubting leads to answers. The only thing he perceived to be certain was his own existence.
"I think, therefore I am" is the first truth of which Descartes is certain. This statement, known as cogito ergo sum, demonstrates Descartes' method of doubt by acknowledging that even if all his perceptions are false, his ability to doubt and think proves his existence as a thinking being.
Philosophically, Descartes was concerned with the existence of reality.
Descartes found it impossible to doubt his own existence. The reason for this was that he felt that thoughts had to come from himself.
Descartes cannot doubt his own existence, as captured in his famous statement "Cogito, ergo sum" - "I think, therefore I am."
Descartes is considered to be the father of modern philosophy.
Descartes hopes to find out what he can know for certain, without any doubt, about the world and nature.
Short answer: Descartes' doubt was like WWI - the doubt to end all doubt. Only by doubting everything could Descartes hope to find anything that was certain (even if the only certainty is that nothing else is certain!).
Descartes had one daughter.
Unlike Descartes, Spinoza believed that the mind was an extension of the body, and vice versa. He thought that there was only one type of substance, a divine substance, of which the mind and body were part. As one thing, the mind and body could interact in harmony, not the discord Descartes was concerned with.
It comes from Descartes famous saying "I think, therefore I am." So he was explaining his belief through you.