XP- and X⁰-movement in the Latin verb: Evidence from mirroring and anti-mirroring

Latin verbs appear to both obey and disobey the Mirror Generalization (Baker 1985), albeit in different inflectional forms (Cinque 1999). Given the importance of the Mirror Generalization to morphosyntactic theorizing, this situation deserves scrutiny. We develop an analysis on which all Latin finite verbs, whether mirroring or anti-mirroring, share a single, simple, virtually invariant derivation, involving one step of head movement (Asp to T) and one step of phrasal movement (vP to [Spec,TP]). On this analysis, the Mirror Generalization is valid for Latin, despite appearances, but it is crucially about structures formed by operations on heads: phrasal movement can give rise to apparent violations of it (Myler 2017). The analysis extends readily to nonfinite forms, solving an anti-mirroring paradox arising among the participles. It also makes correct syntactic predictions. When the verb word is a constituent, it is a TP, and the analysis correctly predicts that it should move as a phrase, not as a head. The analysis also makes correct predictions about the positions of vP-adjuncts, and is fully compatible with what is known about leftward argument movement out of vP. Finally, unlike two competing analyses (Embick 2000; Calabrese 2019), it accounts for anti-mirroring in Latin without any stipulations placing passive Voice in an unexpectedly peripheral position within the verb word. The larger picture that emerges is one in which phonological words need not correspond to syntactic constituents, but can instead be reflexes of linearly contiguous series of morphemes suspended across potentially vast regions of syntactic space (Julien 2002).