The phrase "I think, therefore I am." was spoken by the French philosopher Descartes. He created this phrase to affirm the importance and the existence of absolute doubt. For Descartes it was necessary for man to attain absolute knowledge, but to achieve absolute thought it was necessary for man to doubt everything and everything, including God, the world, all existing concepts and even his own existence. However, man could not doubt that doubt exists, because to doubt it was necessary to think and thought made things real. Therefore, if man is able to think, he is able to exist.
