 Behind this radical extensionalism lies precisely the new strictness with which Carnap applied the Husserlian “bracketing” strategy in 1924—ironically just at the time he abandoned the phenomenological development of the constitutional basis. (More details on Carnap’s extensionalism are to be found in the supplement  Semantics (Section 2).)  The most direct expression of this was a more thoroughgoing and self-conscious rejection of ontology. In the final chapter of the Aufbau, which addresses some philosophical problems to which the constitutional system can be applied, the overriding theme is the irrelevance of ontological questions to the actual constitutional system (Friedman 2007). And in the same year as the Aufbau Carnap published a pamphlet on Pseudo-problems in Philosophy (Carnap 1928b) in which the “problem of realism” is the most prominent example of such pseudo-problems.