This article develops a new approach to a family of hierarchy-effect-inducing configurations, with a focus on Person Case Constraint effects, dative-nominative configurations, and copula constructions. The main line of approach in the recent literature is to attribute these effects to failures of ϕ-Agree or, more specifically, failures of nominal licensing or case checking. We propose that the problem in these configurations is unrelated to nominal licensing, but is instead the result of a probe participating in more than one Agree dependency, a configuration we refer to as feature gluttony . Feature gluttony does not in and of itself lead to ungrammaticality; rather, it can create irresolvably conflicting requirements for subsequent operations. We argue that in the case of clitic configurations, a probe that agrees with more than one DP creates an intervention problem for clitic doubling. In violations involving morphological agreement, gluttony in features may result in a configuration with no available morphological output.
This article develops a general theory of selective opacity effects , configurations in which the same constituent is opaque for some operations but transparent for others. Classical observations of selective opacity lie in the realm of movement. Finite clauses, for instance, are opaque for A-movement but transparent for Ā-extraction, a pattern that generalizes beyond the A/Ā distinction. Using novel evidence from movement-agreement interactions in Hindi-Urdu, I argue that selective opacity also encompasses ϕ-agreement and I propose that the underlying constraint applies, not to movement itself, but to Agree. I develop the novel concept of horizons , which delimit search spaces in probe specific ways by terminating search. They thereby prevent particular probes from searching into them, inducing selective opacity. The horizons account derives an otherwise surprising property of selective opacity effects noted previously: the higher the structural position of a probe in the clausal spine, the more structures are transparent to it. The analysis proposed here unifies improper movement and related selective opacity restrictions, mismatches in the locality of movement and agreement, and intricate interactions between movement types and agreement.