Syntax of either in either... or... sentences.

I propose an analysis of either in either... or ... sentences that relates to a broader generalization about the syntax of all focus-sensitive operators. I argue that either originates inside the disjunction phrase, c-commanding the leftmost contrastive focus. Then it is internally merged as the sister of the disjunction phrase. Either copy of either may be pronounced. When either appears higher than the sister of the disjunction phrase, bare argument ellipsis has occurred in the second disjunct. This analysis of either is consonant with the generalization that all focus-sensitive operators occupy two positions in a sentence (e.g. Cable 2007; Hirsch 2017; and Quek and Hirsch 2017). If this analysis of either is correct, then it not only indicates that either is a focus-sensitive operator, but also adds another data point to this universal generalization. [ABSTRACT FROM AUTHOR]