The co-evolution of pragmatics and grammatical complexity

We propose a Complexity Hierarchy of grammars that map between sound and meaning, beginning with relatively trivial one-word grammars and culminating with the grammars of modern human languages. We argue that the levels in this hierarchy are plausible and necessary stages in the evolution of the contemporary human language faculty. This gradualist scenario has implications for the division of labour between grammar and pragmatics. The simpler grammars in the Complexity Hierarchy place a strong reliance on pragmatics. As grammars become more complex, relatively simple interpretive strategies become more systematic and less dependent on pragmatic inferences. However, pragmatic processes do not disappear. Rather, they change in character: syntax, semantics, and the lexicon trigger highly structured pragmatic phenomena such as presuppositions and implicatures in a systematic and reliable way. In a sense, the more complex the grammar, the more opportunity for such pragmatic niches.