Theoretical Aspects of Movementpossibility that all the grammatical principles involved with Case and its assignment
are bundled together in a single Case theory, paralleling Theta Theory discussed
above. Case theory then applies to S-structure:
(91) Lexicon X-bar theory
D-structure Theta theory
movement
S-structure Case theory
While Theta theory accounts for the distribution of arguments at D-structure, it is the
principles of Case theory that account for the distribution of DP arguments at S-
structure.
We are now in a position to be able to understand at least certain aspects of
movement. Suppose that the principles of Theta theory determine that a DP argument
must sit in position X. Suppose further that position X is not a position to which Case
is assigned. If the DP remains in this position at S-structure, then the Case filter will be
violated and the structure will be deemed ungrammatical. If on the other hand the DP
can move to a position to which Case is assigned, then the movement will enable the
Case Filter to be satisfied and the structure to be grammatical. This kind of movement
might be said to be Case motivated and as we shall see, there are quite a few
movements which follow this pattern. This is not the only motivation for movements,
however, though we will not go into others at this point. The purpose of this section
has been mainly to demonstrate how the interaction of grammatical principles applying
at D-structure and S-structure can provide us with an understanding of movement
phenomena.
2.3 Traces
In the previous sections of this chapter we have concerned ourselves with the positions
in which elements originate at D-structure and the positions they move to at S-
structure. We might term these positions the Extraction site and the Landing site of a
moved element. What is the status of the landing site at D-structure and the extraction
site at S-structure? In (58) we introduced a restriction on movement called the
Structure Preservation principle, which states that movements are not allowed to alter
the basic X-bar nature of a structure. The result of this restriction is that the structure
cannot be much different between D- and S-structure. In particular, we would not
expect landing and extraction sites to appear at one level of representation but be
absent at another. Thus, if we consider a passive structure in which the object moves to
subject position, we can expect the object and subject positions to be present at both
D- and S-structure:
(92) a [DP e] was found [DP the hideout] D-structure
b [DP the hideout] was found [DP e] S-structure