 Carnap’s earliest attempts to develop frameworks, which sought to encompass the conceptual resources of all empirical knowledge, can be found in Der logische Aufbau der Welt (1928a, The Logical Construction of the World), commonly referred to as the Aufbau, its abbreviated original German title. Carnap there focused on sketching a phenomenalist framework in which scientific concepts could be constructed from pure observation. The idea was to have a single framework relative to which any scientific sentence whatsoever (other than purely logical or mathematical ones) could be judged to be cashable or not cashable in empirical, observational terms. However, as Carnap soon realized, the framework failed to address theoretical scientific concepts, disposition concepts, or probabilistic concepts, among much else.