Chapter 3 - Basic Concepts of Syntactic Theoryunderstandable. That (87c) should be ungrammatical is interesting as here we have an
accusative pronoun. In this case the complementiser for is absent, indicating that this
element is in some way responsible for the accusative case in (87a) in which it is
present. This is understandable as this complementiser is similar to a preposition, and
in fact is often called the prepositional complementiser, and as we know, the
complement of prepositions is in the accusative. To account for this let us assume that
Case is rather like -roles and is assigned by certain elements to certain positions. The
prepositional complementiser therefore assigns accusative Case to the subject of the
non-finite clause that it introduces:
(88) [CP for [IP her to be ready ...
Although this might explain why the subject has accusative Case in (87a) and
cannot have nominative Case in (87b), by itself it does not account for why (87c) and
(d) are ungrammatical. To understand what is going on here we must attend more
closely to the facts. Firstly the element that we have assumed to assign accusative Case
to this position is absent and so we might assume that no accusative Case is assigned
in these circumstances. Presumably whatever it is that assigns nominative Case is not
present in a non-finite clause. Therefore in this situation it seems that neither
accusative nor nominative case are assigned to the subject position.
But why would any of this mean that the sentence should be ungrammatical? Only
with an extra assumption can we account for this properly: the pronoun subject needs a
Case. One might think that this is fairly obvious as there is no Case neutral form of the
pronoun: what form would it take if it occupied a Caseless position? However, the
following observations seriously question the assumption that the ungrammaticalities
in (87) have anything to do with Morphological case:
(89) a for Rebecca to be ready on time would be a miracle
b *Rebecca to be ready on time would be a miracle
What we see here is that even a nominal element that does not display morphological
case distinctions cannot occupy a position to which no Case is assigned. Thus the
requirement that a nominal element have Case is nothing to do with the impossibility
of the choice of morphological form when no Case is assigned. Instead, it appears to
be a general requirement that all DPs must occupy a Case position. We call this
requirement the Case Filter:
(90) the Case Filter
All DPs must be assigned Case
The fact that the Case Filter applies to all DPs and not just those that demonstrate
morphological case is strong evidence in favour of the assumption of Abstract Case.
Let us review what we have said so far. We started with the observation that the
position that a DP occupies at S-structure determines its Case. We then claimed that
Case is something applicable to all DPs and finally we proposed a general condition to
the effect that all DPs must receive Case. But putting all this together it is obvious that
the Case Filter can only operate at S-structure as, as we have seen, D-structure
positions are in general irrelevant for determining the Case of an element. Consider the
acc