Introduction

The goal of this chapter is to defend an extended version of the Visibility Criterion (Chomsky 1986a) whereby the link between Theta Theory and Case Theory is generalized. We will argue that the Case-theoretic requirement in the formulation of Visibility should be replaced with a requirement of co-indexation with a functional head; the relevant functional heads being Agreement (Agr) and Tense (T). We will argue that Tense involves two functional heads which are composed into a single chain via the mechanism of selection. This allows the incorporation of aspectual information into the licensing condition. By aspectual we mean the indirect relationship between the utterance time and the time of the event denoted by the verb.

Scottish Gaelic (SG) is particularly relevant to both the extended version of Visibility and to the composition of tense information into a single chain because of two factors: firstly, co-indexation with Agr in SG correlates with word order; and secondly, composition of tense information is transparently reflected in the morphological form of tense and aspect particles. Given these two factors, the extended version of Visibility predicts that certain word orders in SG will be forced or ruled out. This phenomenon is particularly clear with respect to the syntax of measure phrases in the language, which we show to be sensitive to aspectual information.

Generalized Visibility

Typically, argument NPs have to be licensed in two ways: they must be licensed by Theta Theory and they must be licensed by Case.