Head Labeling Preference and Language Change

This dissertation explores a cross-linguistic trend of a diachronic loss of obligatory syntactic movement, which includes the loss of phrasal movement, as in the new observation regarding the unidirectionality of wh-dependency changes—always from fronting to in-situ (e.g. Old to Modern Japanese, Archaic to Modern Mandarin, or Latin to Modern Romance, as well as the loss of head-movement, e.g. V-to-T in English or Swedish. I propose a unified explanation for these changes based on the preference for head-phrase {H,YP} configurations from the perspective of labeling (Chomsky 2013). I argue that the pressures imposed by Labeling Algorithm to maximize head-phrase configuration and minimize the {XP,YP} as well as {X,Y} merger (which are dispreferred from the standpoint of labeling) make the latter ones fragile and prone to loss. I extend this analysis to traditional grammaticalization and additional phenomena, e.g., change of word order and the loss of traditional rightward adjunction. I also investigate specifiers which are more resistant to diachronic change, in particular cases involving multiple movement and show that the loss of movement goes through a single wh-movement stage. I also explore the motivation for the existence of movement in general, discussing its semantic and interface-based triggers. Additionally, I propose an account of V2 where V2 involves two distinct configurations with distinct syntactic mechanisms and licensing conditions, with only one of them being subject to diachronic loss.I also explore the connection between historical change and language acquisition by investigating acquisitional errors of omission in the acquisition of reflexive clitics in Polish. I confirm the connection between acquisition and diachronic change by the history of SE-reflexives in Russian, as well as a broader pattern of acquisition with both monolingual and bilingual children, as well as mixed language varieties and show that all these phenomena provide support for the labeling-based structural preferences argued for in the thesis.