Introduction
Grammaticalization has without a doubt become one of the most productive frameworks for studying diachronic change as well as synchronic variation in language, especially within functional-cognitive linguistics and a usage-based approach. As a framework it has evolved both in terms of the topics studied and its methodology. Grammaticalization has been defined in many different ways, both narrowly as ‘a process that makes lexical or less grammatical units or constructions, more grammatical,’ or more broadly as a ‘change that creates grammar’ or simply ‘grammatical change’ as such. Consequently, different characteristics have been argued to be essential for this type of change and different concrete developments have been labeled “grammaticalization.” Its relation to lexicalization is complex and has been described in various ways, reflecting the wide variety of definitions of the latter. Lexicalization in a fairly general sense refers to the process that leads to new conventionalized lexical items, phrases, or idioms. However, maybe even more so than grammaticalization, the term has been used to encompass conceptually rather disparate phenomena. It need not always involve a diachronic dimension, for instance when it pertains to how more abstract notions, such as motion, manner, and space, are lexicalized, i.e., expressed, in English for instance by such verbs as float, stumble, or swim.
Grammaticalization and lexicalization have been described as being completely opposite types of changes, but also as being orthogonal, distinct processes that may intersect or occur in sequence. Confusion about the nature of grammaticalization, lexicalization, and their relationship to a large extent arises from the various ways in which the lexicon and grammar and their relationship have been defined.
Because of the prolific output of research within these frameworks any introduction to either grammaticalization or lexicalization is necessarily incomplete. This chapter is hence restricted to discussing the main approaches to grammaticalization and lexicalization studies and the changes in focus that they have gone through.
Approaches to Grammaticalization
In this chapter we will restrict ourselves to the narrow sense of grammaticalization, which refers to a specific type of language change in which lexical material develops a more grammatical function and status, and already grammatical material develops more grammatical functions. Such an approach incorporates “unidirectionality,” predicting that grammatical constructions typically have lexical origins, whereas the opposite, lexical items having grammatical origins, is dramatically less common (see below on degrammaticalization).