Stable and unstable language arrangements

One of the hallmarks of diglossia is its stability over long periods of time, a feature it shares with grassroots bilingualism. In both cases the population is territorially stationary, exhibiting no abrupt changes in residence patterns or language choice. If we think, for example, of German-speaking Switzerland, the Basque country and Jammu, north-west India, the language scenarios of these regions have lasted for many generations. No uncertainties or challenges undermined the alternating language-choice conventions for Swiss German/High German, Basque/Spanish and Pashto/Urdu. Stability is a rather vague notion. If, for present purposes, it is defined to mean that nobody alive remembers different language-choice conventions, it implies that basic patterns have been in place for at least four generations. In this sense the three cases, different though they are in terms of sociogenesis and functional allocation of codes, exemplify stable language arrangements.

However, the stability of multilingual arrangements is by no means the rule. Around the globe speech communities live in close proximity, influencing each other. From a language-centred point of view as suggested by Darwin's above-quoted analogy, languages influence each other, expand, contract or die.