godkiller
"We are the Fury"
No. No, he didn't simplify his reasoning to "I think therefore I am," which is a butchered quotation of his french anyways.
That phrase was in the first paragraph of an essay, so obviously Descartes had more to say and his philosophy went further. You might have something to what you're saying if he ended his book with "cognito ergo sum" as some sort of existential epitaph, but no. In fact, that was just a minor part of his larger thoughts.
I never said Descartes didn't say anything other than his "I think therefore I am" philosophy. I said that this is the main thing we take away from his writings because, amonsgt all his other theories, this is the best and most accurate thing he devised. Contrary to what you say above, Descartes' major contribution to philosophy is indeed "Cogito ergo sum". Proof:
Cogito ergo sum - Wikipedia
"Cogito ergo sum[a] is a Latin philosophical proposition by René Descartes usually translated into English as "I think, therefore I am".
As Descartes explained, "[W]e cannot doubt of our existence while we doubt … ." A fuller form, penned by Antoine Léonard Thomas, aptly captures Descartes’s intent: dubito, ergo cogito, ergo sum ("I doubt, therefore I think, therefore I am").https://en.wikipedia.org/wiki/Cogito_ergo_sum#cite_note-3
This proposition became a fundamental element of Western philosophy, as it purported to form a secure foundation for knowledge in the face of radical doubt. While other knowledge could be a figment of imagination, deception, or mistake, Descartes asserted that the very act of doubting one's own existence served—at minimum—as proof of the reality of one's own mind; there must be a thinking entity—in this case the self—for there to be a thought."