 In the light of the foundational debate, the following years were rich in seminal work: new paradoxes were discovered (Berry, Grelling-Nelson), an old paradox—the Liar—showed up again, a comprehensive view of the contradictions of logic and mathematics was masterfully outlined in the opening section of Russell’s 1908 paper and the preceding Russell 1906a, while a conceptual distinction between two kinds of paradoxes was set forth in Peano’s paper of 1906. Also, the basic ideas of predicativity emerged in the discussion between Poincaré, the leading mathematician of the time, and Russell. Even more important for the history of mathematical logic, fundamental technical advances for solving the paradoxes and shaping the foundations of logic and mathematics were made: Russell’s theory of (ramified) types and Zermelo’s axiomatization of set theory.