 Łukasiewicz once declared somewhat immodestly that the discovery of many-valued logics was comparable to that of non-Euclidean geometries (SW 176). Whatever their significance, Łukasiewicz’s hopes for such logics have not been realized in the way he anticipated. The semantics and pure mathematics of multivalued logics have flourished, leading to the development of MV-algebras in use for the algebraic semantics of Łukasiewicz’s logics. Infinite-valued or fuzzy logic has its own mathematics, and prominent among its developers is the Czech mathematical logician Petr Hájek, whose work is influenced by that of Łukasiewicz. Fuzzy logic is found in many practical applications, where it is used to deal with vagueness, inexactness, or lack of knowledge, whether these are the same or different. But Łukasiewicz’s championing of multivalence in the analysis of modality has been almost universally rejected, and the logic of modality has inexorably followed other paths, mostly bivalent, non-extensional ones. His final logic Ł has resisted consensual interpretation, and is regarded as at best an oddity and at worst a dead end.