incompleteness theorem

incompleteness theorem, in foundations of mathematics, either of two theorems proved by the Austrian-born American logician Kurt Gödel. In 1931 Gödel published his first incompleteness theorem, “Über formal unentscheidbare Sätze der Principia Mathematica und verwandter Systeme” (“On Formally Undecidable Propositions of Principia Mathematica and Related Systems”), which stands as a major turning point of 20th-century logic. This theorem established that it is impossible to use the axiomatic method to construct a formal system for any...