‘Any natural language consists of rules which are inherently social and normative.’ It is the purpose of this chapter to establish the truth of this claim and to show that it is significant or non-trivial. The argument is based on the ineluctable place of normativity in any consistent account of language, as shown by Wittgenstein’s private-language argument. Furthermore, the paper discusses the relation between semantics and pragmatics and elucidates the ontology of “the social”, showing that normativity implies a particular form of intersubjectivity: common knowledge. Finally, it spells out ramifications of the argument for the empirical study of language within diachronic linguistics, psycholinguistics and linguistic typology. It concludes by pointing to the possible sources of the anti-normative bias in much of theoretical linguistics.