The inevitable reason why all languages are similar

It is an old observation that all languages, despite apparent differences on surface level, seem to be significantly similar in their core structure. It was hypothesised by the 17th century Port-Royal philosophers Lancelot and Arnauld that all languages are governed by the same universal rules, being based on the one and only logic available for mankind. The rules of this universal grammar, applicable for all languages, would need to be reconstructed in order to discover the essence of language. (Jermołowicz 2003.) Although the philosophy of Port-Royal enjoyed great interest until the beginning of the nineteenth century, attempts to reconstruct such a grammar ultimately failed. The quest for a universal grammar was eventually revived by Noam Chomsky, although with an important departure from the Port-Royal Grammar: according to Chomsky, the universal syntactic principles are genetically encoded in humans. (Jermołowicz 2003, Chomsky 1972, Christiansen & Chater 2008.) What is more, in Syntactic Structures, Chomsky (1957) introduced Emil Post's mathematical production system to linguistics as rewrite rules (Pullum 2010, cf. Post 1943). With this novel method it may have been anticipated that Universal Grammar (UG) would be reconstructed as a formal grammar. Quite conversely, Chomsky's UG seems to have remained on the level of a