Introduction

The goal of this chapter is to sort out the roles that ‘formal’ and ‘functional’ factors have been said to play in language change. An immediate challenge is to provide these two terms with enough content so that there is no uncertainty about what specifically is at stake in any explanation of a change that incorporates one of these two terms. It is not uncommon, for example, to encounter statements in the literature such as: ‘Formal pressure was responsible for the loss of instrumental case in English’ or ‘Grammatical oppositions with a low degree of functionality are more likely to be lost than those with a high degree.’ Unfortunately, such claims are often not accompanied by a sufficiently precise characterization of the notions ‘formal pressure’ or ‘degree of functionality’ to allow them to be adequately evaluated. Our first task, therefore, is to specify as precisely as possible what a ‘formal explanation’ and a ‘functional explanation’ might consist of.

Throughout this chapter a ‘formal explanation’ will designate one in which principles governing the organisation of grammars are said to play a central role. A ‘functional explanation’, on the other hand, refers crucially to properties of language users, in particular to their interest in producing and comprehending language rapidly, to their states of consciousness, or to aspects of their behaviour.