 This variety of conflicting viewpoints contributed much to the overall confusion, but there was more. In addition to the paradoxes discussed above (set-theoretic paradoxes, as we say), the list of “logical” paradoxes included a whole array of further ones (later called “semantic”). Among these are paradoxes due to Russell, Richard, König, Berry, Grelling, etc., as well as the ancient liar paradox due to Epimenides. And the diagnoses and proposed cures for the damage were tremendously varied. Some authors, like Russell, thought it was essential to find a new logical system that could solve all the paradoxes at once. This led him into the ramified type theory that formed the basis of Principia Mathematica (3 volumes, Whitehead and Russell 1910–1913), his joint work with Alfred Whitehead. Other authors, like Zermelo, believed that most of those paradoxes dissolved as soon as one worked within a restricted axiomatic system. They concentrated on the “set-theoretic” paradoxes (as we have done above), and were led to search for axiomatic systems of set theory.