Which existential philosopher said: "I am not that that is not not I"? I thought it was Heidegger.?

Question

I thought it was Heidegger but I did a search and found no results for the proof.

Answer 1

Certainly, it could not be Descartes who lived in 17thC and was a major thinker associated with the Age of Reason especially known for his Cartesian, "I think, therefore I am." Existentialism is a more recent philosophy dating to Kierkegaard in 19th Century although the thought could be traced to Fyodor Dostoevsky a little earlier.

Existentialism peaked after the world world wars with such philosophers as Nietzsche, Camus, Heidegger, Marcel, Sartre etc in the 20thC when the turned Descartes up-side-down with the witty, "I exist, therefore I am."

The quote actually comes from Heidegger.
Heidegger describes being as a process of misunderstanding the authentic self. Caught up in an everyday world of all that appears closest and most familiar to us, we believe that our existence can be explained by what we know well. But ontologically, our most authentic selves lie in what is most mysterious and strange—what appears to be furthest from us. Confronted with authentic being, we feel a sense of terror in the face of the unknown. The dangerous lover narrative makes the same argument about ontology—that our “true” selves reside in what is most strange and enemy-like, in the dangerous other.

Answer 2

I think you are on the right track, 20th century Continental. Maybe try Buber's "I and Thou".

I have read most Descartes and that goes well beyond his syntax (cogito sum / cogito ergo sum).

Answer 3

Sounds like Descarte in his logical progression "Cogito ergo sum"

Answer 4

"I am not that that is not not I ?????wtf that sounds like something a homeless person would say