In this book we have introduced the major theoretical and methodological issues under discussion in work on grammaticalization. As indicated in Chapter 1, the approach we have taken is two-pronged. Specifically, we have considered grammaticalization as (ⅰ) a research framework for studying the relationships between lexical, constructional, and grammatical material in language, whether diachronically or synchronically, whether in particular languages or cross-linguistically, and (ⅱ) a term referring to the change whereby lexical items and constructions come in certain linguistic contexts to serve grammatical functions and, once grammaticalized, continue to develop new grammatical functions. The term is, however, used in different ways by different linguists, and we have outlined some differences in approach, most especially in Chapters 2 and 5.

Chapters 3 and 4 discussed the major mechanisms of change that can lead to grammaticalization: reanalysis and analogy at the morphosyntactic level, conceptual metonymy and metaphor at the semantic, both driven initially by pragmatic inferencing. We have argued that grammaticalization can be thought of as the result of the continual negotiation of meaning that speakers and hearers engage in in the context of discourse production and perception. The potential for grammaticalization lies in speakers attempting to be maximally informative, and in hearers attempting to be maximally cooperative, depending on the needs of the particular situation. Negotiating meaning may involve innovation, specifically, pragmatic, semantic, and ultimately grammatical enrichment.