An Empirical and Theoretical Study on the Demise of Null Expletive Subjects in the History of English

本研究在极简程序的理论框架下，探讨了英语历史上零主语（pro）的消亡、动词秒（V2）的消失和动词屈折形态的衰落之间的因果关系。结果表明，pro的消亡直接由V2的丧失引起，间接由言语屈折变化的减少引起。我开发了一个理论模型来解释问题中的变化，并通过将其应用于另一个历时变化，即心理动词类的非主格体验者的丧失，来证实其有效性。

This study investigated the causal relation among the demise of null subjects (pro), the loss of verb second (V2), and the decline of verbal inflectional morphology in the history of English under the theoretical framework of the minimalist program. It was demonstrated that the demise of pro was caused directly by the loss of V2 and indirectly by the decline of verbal inflection. I developed a theoretical model to account for the change in question and confirmed its validity by applying it to another diachronic change, the loss of non-nominative Experiencers of the psych-verb like.