The Guiding Framework
Language has a fundamentally social function. Processes of human interaction along with domain-general cognitive processes shape the structure and knowledge of language. Recent research across a variety of disciplines in the cognitive sciences has demonstrated that patterns of use strongly affect how languages are acquired, used, and change over time. However, there is mounting evidence that processes of language acquisition, use, and change are not independent from one another but are facets of the same system. We argue that this system is best construed as a complex adaptive system. Language as a complex adaptive system involves several basic components: the system consists of multiple agents (the speakers in the speech community) interacting with one another; the system is adaptive, that is, speakers' behavior is based on their past interactions, and current and past interactions together feed into future behavior; and a speaker's behavior is the consequence of competing factors ranging from perceptual constraints to social motivations.
The advantage of viewing language as a complex adaptive system is that it provides a unified account of seemingly unrelated linguistic phenomena as properties of a single system. These phenomena include: variation at all levels of linguistic organization; the probabilistic nature of linguistic behavior; continuous change within agents and across speech communities; the emergence of grammatical regularities from the interaction of agents in language use; and stage-like transitions due to underlying nonlinear processes. The complex adaptive systems approach reveals commonalities in many areas of language research, including first and second language acquisition, historical linguistics, psycholinguistics, language evolution and computational modeling. Moreover, it provides new directions for future research.