Diachronic data analysis supports and refines conceptual metaphor theory

Our empirical analysis confirms the fundamental assumption in conceptual metaphor theory that metaphors are enduring linguistic and cognitive structures, not merely rhetorical figures. Complex systems tools identified a metaphor network with systematic separation of abstract and concrete categories, and two significant metaphorical processes: mappings from concrete to abstract topics and the emergence of new mappings between concrete domains. Metaphors concentrate on two small sets of everyday topics. One within the concrete group serves as both strong source and target domains, while the other, in the abstract group, primarily acts as targets. These findings can serve as confirmation that metaphor is a creative process emerging primarily from difference and tension between topics which allow (re-)conceptualizations and the display of new similarities.Author summary: Metaphor theory examines how human thinking, conceptualizations and ideas, arise through new transfers of experiential and earlier acquired structures across thematic domains. These transfers are to some extent reflected in language change over time through metaphor conventionalization. We have carried out a systematic study of such metaphorically generated linguistic changes across the full thematic network of the English language. This analysis revealed several systematic features of metaphorical language change. Two metaphorical processes occur particularly frequently: Metaphors from concrete, often body-related topics, into more abstract topics, which in turn rarely act as metaphor sources, are the most common. The second process are metaphors that transfer and re-conceptualize words within the more concrete topics. Furthermore, we show that metaphorical connections between topics are stable in the long term and investigate the conceptual ordering of topics that results from their metaphorically related neighbors.