So how many languages are there in the world? The various notions of how to individuate them offer a fairly wide range of answers, none of which seems overwhelmingly correct. ‘The unity of human language’ concludes that, in its most basic aspects, human language is so different from any other known system in the natural world that the narrowly constrained ways in which one grammar can differ from another fade into insignificance. The principles governing the systems of sounds, words, and meanings are largely common across languages, with only limited possibilities for difference. While these differences may seem important, all are relatively minor variations on the theme of human language.