 Carnap set to work, after his arrival in Vienna, to solve these two problems. He embarked on a major project to explore “general axiomatics”, in which he sought to show that Hilbertian axiomatics could be accommodated within the Wittgensteinian representational framework—i.e., he sought to show that the Hilbertian “method of bifurcation”, (into metalanguage and object language), while mathematically useful, could ultimately be reduced to a Wittgensteinian single language. The immediate goal was to prove a fundamental completeness theorem, purporting to show that a consistent axiom system is categorical just in case it is decidable (Awodey &amp; Carus 2001). After three years of concentrated work on this project (a substantial manuscript of several hundred pages survives in Carnap’s papers), Alfred Tarski convinced him that this theorem was defective, and that Carnap’s attempt to work within a single language failed to capture the metamathematical concepts fully (but see Schiemer 2013). And late in 1930, Gödel actually showed that an important special case of Carnap’s theorem was false: second-order arithmetic, though categorical, is not decidable. This famous result put an end to Carnap’s project of fusing Hilbert and Wittgenstein.