"I think, therefore I am" is a iconic phrase said by French philosopher René Descartes, which marked the vision of the Enlightenment movement, placing human reason as the only form of existence.
René Descartes (1596 – 1650), considered the founder of modern philosophy, reached the conclusion of this famous phrase while seeking to outline a methodology to define what would be the “true knowledge".
The philosopher and mathematician wanted to obtain absolute, irrefutable and unquestionable knowledge.
Even though he attended the best universities in Europe, Descartes felt that he had learned nothing substantial (apart from mathematics) in his studies.
All scientific theories ended up being refutable and replaced by others, there was no real certainty beyond doubt. Descartes, then, began to doubt everything, including his own existence and the world around him.
However, Descartes found something he could not doubt: doubt. According to the philosopher's thought, when he doubts something he would already be thinking and, because he is doubting, he would soon be thinking. Descartes understood that in doubting he was thinking, and because he was thinking, he existed. In this way, his existence was the first irrefutable truth he encountered.
Thus, Descartes published in his book “The Discourse of Method”, published in 1637, the summary of his thought in the sentence: think now, donc je suis (original publication in French), which was later translated into Latin ego cogito, ergo sum sive exist. Despite this, in Latin this phrase is translated only as cogito ergo sum.
See also the meaning of Enlightenment.
original sentence: "Pusque je doute, je think; shimmer already think, it already exists"
Author: Rene Descartes
Book: Discours de la Method / "The Discourse of the Method"
Year: 1637
Local: Leiden, Netherlands