Clause structure folding and the "wh-in situ effect"

Why must a coordinative head show up before an adverbial wh-phrase in situ in Italian? In this article, I explore this rather neglected fact, showing that it reveals an otherwise hidden structure. More specifically, I propose that the coordinative head does not directly merge with the wh-phrase it precedes; rather, it takes a full clausal complement, inducing remnant movement and stranding of the highest wh-phrase. This configuration yields the observed word order and explains many properties of these constructions by means of independent locality conditions. I argue that it is a rescue strategy languages may adopt to meet a structural property of the left periphery, and I address some questions that the comparative perspective raises.