Attunement: a new principle of optionality

Functionalist linguists generally maintain that language favours exclusive form-meaning mappings, adhering to principles of isomorphism or no synonymy. Variationist linguists, by contrast, emphasise that language is rife with alternative ways of saying the same thing, aligning with a principle of optionality. This theoretical piece argues that the apparent tension between these perspectives can be resolved by attending to two sets of background assumptions: what counts as meaning, and how communication works. We contend that a usage-based theory of meaning, encompassing semantic, pragmatic, and social information, is not only compatible with variation but entails it; and that a cognitive theory of communication, informed by good-enough production and relevance-theoretic heuristics, explains why optionality phenomena emerge in language use without compromising isomorphism in linguistic knowledge. We subsume these insights under a newly proposed Principle of Attunement. We explore the explanatory scope of attunement for register-driven variation, the expendability cline, creative language use, and language change, before introducing the contributions to the special issue.