CentralNotice From Wikipedia, the free encyclopedia Jump to: navigation , search For Paul Curry's optical illusion and dissection puzzle, see Missing square puzzle . Curry's paradox is a paradox that occurs in naive set theory or naive logics , and allows the derivation of an arbitrary sentence from a self-referring sentence and some apparently innocuous logical deduction rules. The paradox is named after the logician Haskell Curry . The paradox may be expressed in natural language and in various mathematical settings, including certain forms of set theory , lambda calculus , and combinatory logic . It has also been called Löb's paradox after Martin Hugo Löb . [ 1 ] 1 Natural language 1.1 Proof that the sentence is true 1.2 Formal logic 1.3 Naive set theory 1.4 Logic with a string Eval function 1.5 Lambda calculus 1.6 Combinatory logic 2 Discussion 2.1...