Putting connections centre stage in diachronic Construction Grammar

Construction Grammar conceptualizes language as a hierarchically organized network of constructions, defined as conventional pairings of form and meaning. Importantly, constructions are interlinked: vertical links connect lower-level constructions with their higher-level parents; horizontal links connect sister constructions on the same level. While the importance of vertical connections is well-established, horizontal connections have received only little attention in the theoretical literature so far. The power of horizontal connections stems from their ability to express syntagmatic and paradigmatic relations. By means of two classic case studies, we will show how shifts in similarity relations, that derive from shared horizontal connections down to the utterance level, enable changes in paradigmatic affiliations to constructions higher-up in the network. Our first case study relates the emergence of a new construction, [be going to INF], to the co-occurrence of its three constituent constructions in specific contexts that were favourable to a holistic interpretation. The second case study describes how a shared set of strong syntagmatic connections strengthened the paradigmatic ties between periphrastic do and the modal auxiliaries, ultimately causing periphrastic do to break free from its lexical origins and fully adopt its new role as auxiliary. Generally, while constructional nodes cannot be reduced to horizontal connections between forms and/or meanings, knowing the nature of such connections is essential to a full understanding of both the emergence of new constructions as well as the consolidation of existing ones.