 Here is an illustration from Szabó (2000b). Suppose English is compositional. Take two of its non-synonymous sentences—say, ‘Elephants are grey’ and ‘Julius Caesar was murdered on the ides of March’—and define Crypto-English as the language with the same expressions, the same syntax and almost the same semantics as English. The only difference is that if a sentence is synonymous in English with one of the two designated sentences, then it is synonymous with the other in Crypto-English. We assumed English is compositional and hence that there is no pair of non-synonymous complex expressions in English with identical structure and pairwise synonymous constituents. Trivially, the same must hold for Crypto-English as well. But intuitively, Crypto-English is not compositional. The structure and the meanings of constituents of the Crypto-English sentence ‘Elephants are grey’ cannot determine what this sentence means in Crypto-English—if they did then the structure and the meanings of constituents of the English sentence ‘Elephants are grey’ would have to determine what ‘Julius Caesar was murdered on the ides of March’ means in English.