To bring linguistic theory back in touch with commonplace observations concerning the resilience of language in use to language change, language acquisition and ungrammaticality, Pullum and colleagues have argued for a ‘model-theoretic’ theory of syntax. The present paper examines the implications for linguists working in standard formal frameworks and argues that, to the extent that such theories embrace monotonicity in syntactic operations, they qualify as model-theoretic under some minor modifications to allow for the possibility of unknown words.
