JOURNAL of HISTORICAL SYNTAX Volume 9, Article 15: 1–44, 2025 ⋅ DOI: 10.18148/hs/2025.v9i13.187 BASQUE V2 EFFECTS IN DIACHRONY ∗ MAIA DUGUINE CNRS-IKER GEOR G A. KAISER UNIVERSITÄT KONSTANZ ABSTRACT This paper explores the evolution of verb-second (V2) patterns in Basque wh-interrogatives from the Archaic period (14-16 th c.) to later periods. While in Modern Basque a systematic “residual” V2 system in wh-interrogatives is observed, in Archaic Basque the patterns appear to be mixed: synthetic verbs display systematic V2 order, whereas analytic verbs allow intervening material between the wh-phrase and the verbal complex. We put forth a multifactorial analysis of Archaic Basque interrog- atives, assuming that in analytic constructions independent syntactic and morphophonological properties of auxiliaries interact with the syntax of V2 in such a way that they ‘hide’ its effects on word order. The change from Archaic to Modern Basque involves a simple change in the properties of T, independently of the syntax of V2. 1 LANGUAGE VARIATION AND CHANGE IN V2 ORDERS The notion of verb-second (V2) covers a set of phenomena with broad cross- linguistic variability. Distinctions have been made between “strict/exact V2” vs. “relaxed/at least V2”, where the latter involves a high number of non- V2 orders (cf. among others Jouitteau 2010, Holmberg 2015, Lohnstein & Tsiknakis 2020, Poletto 2013, Wolfe 2019, Wolfe & Woods 2020). Then, what has been dubbed “residual” or “partial” V2 is observed in languages with- out a proper V2 system, but in which ordering patterns in specific structures –typically interrogatives– mirror the V2 pattern (“V2 effects”), as is the case, ∗ This work was funded by the joint ANR-DFG project Uncovering V2 effects: An interface-based typology (UV2) (ANR18-FRAL0006 and DFG-411069456), as well as by the projects ANR-21- CE27-005, ANR-22-CE28-0024-02, and PaRL (Région Nouvelle Aquitaine). We would like to thank the reviewers, as well as the editors of the volume, the participants of the workshop A multifactorial approach to word order change and the members of the UV2 project for their useful comments on previous versions of this paper. ©2025 Duguine & Kaiser This is an open-access article distributed under the terms of a Creative Commons License (creativecommons.org/licenses/by/4.0).