Most people, if asked what a language is, would almost certainly answer in terms of ‘sounds’, ‘words’ and ‘sentences’. They would probably also refer to something less clearly defined which they might call ‘meaning’. And they might just possibly add something about the purposes that language – both spoken and written – serves in the interpersonal transactions that constitute so large a part of everyday life. Such an ordering of priorities no doubt owes much to the way in which ‘language’ is encountered during the process of education: in dictionaries, in the form of comprehension exercises, and in lessons on grammar and spelling. It also corresponds quite closely to the relative emphasis that has been given to the various aspects of language in the long tradition of serious study that goes back as far as Aristotle and even earlier.

The same emphasis on sounds, words and sentences, treated as units within a formal system, has also characterised the greater part of the work carried out in the present century by linguists and others who have attempted to study language ‘scientifically’.