The Rise of Positional Licensing

Case is defined by the positive values [+H(ighest) R(ole)], [+L(owest) R(ole)], which are assigned to the Th-roles according to their relative position on the Th-role hierarchy (itself a projection of semantic form). (25) a. [+HR] is assigned to the highest role. b. [+LR] is assigned to the lowest role. Our notion of abstract Case resembles GB’s in that it is a syntactically assigned feature complex, but we construe it in a somewhat different way since abstract Case is not by itself a licensing property, but a set of featurally expressed constraints on morphosyntactic case. The licensing property is rather the successful unification (compatibility) of the case features at the different levels, in particular the unification of abstract case and morphosyntactic case. By (25), the three ordered Th-roles of the verb show projected in (22a) (shower, showee, thing shown) are assigned the abstract Case features in (26). (26) [ λz [+LR] ] [ λy [ ] ] [ λx [+HR] ] [x CAUSE [CAN [y SEE z ] ] ] The sole role of an intransitive verb gets both [+HR] and [+LR], and the middle role of a three-place predicate gets neither [+HR] nor [+LR]. The result is an inventory of four abstract structural cases, in Dixonian terms “A”, “S”, “O”, and “D”. (27) a. S: [+HR,+LR] b. O: [+LR] c. A: [+HR] d. D: [ ] Not explicitly indicated in (26) is the fact that all three Th-roles bear a feature of abstract structural case (say [+SC]), which is subclassified by the features [LR, HR]. For typographical simplicity, this will be tacitly assumed to be present in every bracketed feature matrix that follows, with the absence of structural case thus symbolized by the absence of a bracket. Because the case features are intrinsically relational, there can be at most one [+HR] role and at most one [+LR] role per argument structure. On the