On Headless XP-Movement/Ellipsis

I make two proposals in this article: (a) an economy condition on the operation Copy, which states that Copy should apply to as small an element as possible, and (b) the “two types of head movement” hypothesis, which states that Universal Grammar allows head movement via substitution as well as head movement via adjunction. I argue that with these proposals, we can not only explain two generalizations about what I call headless XPs, but also attribute crosslinguistic variation in the applicability of these generalizations to parameters that are responsible for the availability of multiple specifiers.