Carnap and Phenomenology: What Happened in 1924?

Andre Carus (Hegeler Institute) gives a talk at the MCMP workshop "Influences on the Aufbau" (1-3 July, 2013) titled "Carnap and Phenomenology: What Happened in 1924?". Abstract: The sketch of the Aufbau system in "Vom Chaos zur Wirklichkeit" (1922) employs phenome- nology to describe the system basis, as do other writings before 1924. But in January 1925, we find a new principle of " ̈Überwindung der Subjektivität" and a new emphasis on "Einheit des Gegenstands- bereichs." Russell's "construction principle" becomes the motto of the published book. The earlier ap- proach is explicitly rejected. Why this radical change? This question is discussed here on the basis of evidence from Carnap's papers, and a somewhat unexpected conclusion is reached.