In the 1920s, Descartes made the statement "Cogito Irgo Sum" (I think, therefore I am). If a person is thinking, they must exist. He believed consciousness was in 2 parts (Dualism): me, and the world. This was accepted by all until 1927, when Heidegger claimed this was not true, all you can say is that there are ideas. This poses the question: What are ideas? Heidegger says that they are intentions, moods, ambiguity and the act of choosing.If you don't click through, you'll miss the cool new duckrabbit picture.