Heidegger - Descartes & Subjetividade

"He began by doubting everything, but this doubt finally did run into something that could no longer be doubted, for, inasmuch as the doubter doubts, he cannot doubt that he is present and must be present in order to doubt at all. As I doubt I must admit that 'I am'. The 'I', accordingly, is the indubitable. As the doubter, Descates forced man in to doubt in this way; he led them to think of them self, of their 'I'. Thus the 'I', human subjectivity, came to be declared the center of thought. From here originated the I-viewpoint of modern times and its subjectivism".

Martin Heidegger - Modern Science. Metaphysics, and Mathematics (1967)