Government and Binding Theory/Case Filter

An important concept in Case Theory is the Case Filter. It posits that all DPs must have abstract case.

Case Filter Every phonetically realised DP must have abstract Case.

This explains why DPs and APs never take PP complements:

(1a) *the help John
(1b) *happy the incident

Does this remind you of anything? Yes, we briefly mentioned this puzzle near the beginning of the book!

Case Filter and A-Movements

A-movements are motivated by the Case Filter. Let's use an example.

(2a) D-structure of (3b):  — was killed he
(2b) S-structure of (3b): he was killed —

To satisfy the Extended Projection Principle, it seems that we can simply fill up the subject position of (2c) using a pleonastic it, but this is not possible:

(2c) *It was killed he

Why is this? The Case Filter comes to the rescue. he cannot be assigned Case in (2a) because passive verbs cannot assign accusative Case, as we will see later. Thus (2c) is not possible. Instead, the DP in object position moves to subject position in S-Structure, where the inflection assigns nominative Case to it.

Burzio's generalisation

Burzio's generalisation captures the properties of unaccusative, raising and passive verbs at once:

Burzio's generalisation A verb without an external argument cannot assign accusative Case. A verb that fails to assign accusative Case does not have an external argument.

Burzio's generalisation relates the θ-marking and case-assigning properties of verbs. Verbs that can assign accusative Case do not have external arguments, and vice versa. This necessitates movement:

Verb	Internal argument	External argument	Nominative Case	Accusative Case
Transitive (e.g. take)	✓	✓	✓	✓
Intransitive (e.g. jump)		✓	✓	✓
Unaccusative (e.g. come), ergative verbs (e.g. melt) passive (e.g. be eaten), raising (e.g. seem)	✓		✓

You may be wondering how intransitive verbs assign accusative Case. The answer lies in cognate objects. Intransitive verbs can carry cognate objects, but not unaccusative, ergative, passive or raising verbs:

(3a) He lives a great life.
(3b) *He came a great coming.
(3c) *He melted a great melt. (3d) *He was killed a great kill.
(3e) *He appeared a great appearance.

We can now also explain raising verbs:

(4a) It seemed that he had finished his homework.
(4b) *It seemed that he to have finished his homework.
(4c) He seemed to have finished his homework.

(5a) It is thought that he had finished his homework.
(5b) *It is thought that he to have finished his homework.
(5c) He is thought to have finished his homework.

In (4a) and (5a), the finite inflection assigned nominative Case to he, so it's all good. We used a pleonastic subject as no external argument could be assigned. In (4b) and (5b), to cannot assign nominative Case to he. He violated the Case filter, resulting in (4c) and (5c), in which the subject of the lower IP moved to the beginning.