This paper uses Old Spanish as a case study to argue that verb-second (V2) syntax is not monolithic but instead involves a split between external merge (EM) and internal merge (IM) into the C-system. Building on Holmberg’s (2020) findings on Swedish, it demonstrates that the enclitic and proclitic patterns in Old Spanish finite main clauses serve as diagnostics for whether a V2 constituent reaches the preverbal field via EM or IM, reflecting a broader distinction between formal V2 and scope/discourse-related V2. The high frequency of enclisis in Old Spanish suggests a predominance of EM-driven V2, in contrast to Holmberg’s assessment of Swedish, where EM-driven V2 is claimed to be more restricted.

The paper proposes a mixed model of V2 syntax, integrating EPP-driven merge into Spec-FinP (Haegeman 1996) with interpretively motivated Criterial movement (Rizzi 2006; Samo 2019). Residual V2 reflects the resilience of the interpretive component, with its assumed Spec-head configuration (Poletto 2000) reinterpreting verb movement to Fin0 as movement to the Criterial head. The model provides a new perspective on the interplay between formal and interpretive aspects of V2 syntax, with implications reaching beyond Old Spanish.