ABSTRACT
There has been much discussion of valency alternations in linguistic theory, and in Government-Binding (GB) theory (Chomsky, 1986a, 1986b) in particular. A construction which has received special attention is the passive voice. It is widely recognized that a great many languages have a productive alternation in which a transitive verb becomes intransitive. The direct object surfaces as the subject of the derived verb form, leaving the former subject either totally unexpressed (albeit ‘implicit’), or expressed solely as an optional adjunct phrase, frequently signalled by an oblique case marker or adposition. It is generally assumed in GB theory that passive verb forms fail to assign an external theta role, that is, a semantic role corresponding to that of the active subject. In GB theory, canonical passive constructions reflect Burzio’s Generalization. This states that predicates which fail to assign an external role also fail to assign objective Case. This means that such verb forms are unable to license a surface direct object. Hence, when a predicate which selects a direct object (i.e. which has an internal argument) appears in the passive voice, that internal argument surfaces as the subject of the constructions. This is because the subject position is the only position in which it can be assigned Case. By the Case Filter, all overt NPs must receive Case (or the equivalent), thus, the promotion of the old direct object to subject position has the appearance of an obligatory transformation.
