Did Descartes Invent 'I Think Therefore I Am'?

Saint Augustine presented a similar idea about 1200 years before Descartes, saying 'If I am mistaken, I exist.' However, Descartes' originality lies in using this insight to build a complete philosophical system rather than a passing observation.

The canonical formulation (Cogito, ergo sum) appeared in Descartes' 'Principles of Philosophy' (1644) and 'Discourse on Method' (1637). However, in his masterwork 'Meditations' (1641), Descartes used a different formulation: 'I am, I exist' (Ego sum, ego existo) without the explicit 'therefore.'

There is ongoing philosophical debate about this. In 'Principles' Descartes presented it as logical inference, but in 'Meditations' he emphasized it as immediate intuition, not complex logical deduction. Philosophers like Hintikka argue it's not a logical argument but existential 'performance' self-evidencing itself.

This is indeed correct. Even if a powerful demon tried to deceive me, I must exist in order to be deceived. However, this doesn't prove the existence of anything else external. Descartes himself acknowledged he needed additional arguments to prove God and the material world.

Nietzsche strongly criticized Descartes' formulation and proposed the opposite: 'I am, therefore I think' (Sum, ergo cogito). Nietzsche believed existence is primary and thinking is a consequence of it, opposite to Descartes' position.

Critics like Pierre Gassendi and physicist Georg Christoff Lichtenberg argued that Descartes only proves 'thinking occurs' not necessarily 'I exist.' There could be thinking without a definite 'I.' However, Descartes' defenders respond that thinking cannot occur without something that does the thinking.

There is no philosophical consensus. Contemporary criticisms include logical issues, the nature of self, and the impossibility of proving external reality. Some philosophers fully accept the idea while others find it incomplete or conditioned by specific assumptions.

This is absolutely correct. Descartes' methodical procedure required doubting everything—even our senses and dream perceptions—to reach an indubitable truth. Only when he found that even in attempting total doubt, he must exist, did he arrive at the cogito.