As reflected in many chapters in this book, English is probably the most well studied language in the history of linguistics, so that there is a vast pool of examples of both excellent description and insightful theoretical analysis to be found in the literature. Still, concepts like ‘description’ and ‘theory’ are anything but clear. The issue of what the defining characteristics of a ‘theory’ are has received a lot of attention in philosophy and the history of science. However, in terms of distinguishing a theory from a description, that literature is not terribly helpful. Even though ‘theory’ may appear to be the more complex of the two notions, there are issues also with what constitutes a description of a language.

A description of any language should contain an inventory of the building blocks; sounds and morphemes, roughly. It should also contain the rules for how those elements can be combined; phonotactic constraints, information about which differences between sounds are distinctive, how morphemes can be combined to form words, and how words can be combined to form phrases. In spite of the attention that the language has received, no complete description of English in this sense has yet been provided. To take but one example, even though there are many insightful descriptions of the English passive, the exact rules that allow for sentences such as This road has been walked on have not been provided. The view of a grammatical description just described coincides with the original conception of a ‘generative’ grammar. A generative grammar in that sense takes the building blocks of a language and ‘generates’ all and only the grammatical sentences of that language. Needless to say, no complete such grammar has been defined, not for English and not for any other language.