Chapter 3 - Basic Concepts of Syntactic Theorythese two positions are not the same then X will have to move from its D-structure
position to the required S-structure position. Thus, explaining movement is a matter of
finding out the principles which determine the distribution of elements at D- and S-
structure.
Turning to D-structure first, an important consideration which has been present in
all developments of this concept, first proposed by Noam Chomsky in the 1950s, is
that D-structure positions are somehow basic. For example, in a passive sentence, what
sits in the subject position at S-structure is interpreted as the object of the verb and
hence is assumed to occupy the object position at D-structure:
(63) S-structure: Ken was confused
D-structure: was confused Ken
The idea is that the way an element is interpreted in terms of its thematic status
indicates its D-structure position and thus if something is interpreted as an object it
will be in an object position at D-structure. Moreover, an element that is interpreted as
the subject or object of a predicate will be in the relevant subject or object position of
that predicate at D-structure:
(64) S-structure: Ken was considered to be confused
D-structure: was considered to be confused Ken
In this example, although Ken is sitting in the subject position of the verb consider,
this element is interpreted as the object of confused and thus is in the object position of
this predicate at D-structure.
D-structure then is a pure representation of thematic relations. Anything which is
interpreted as the subject or object of a given predicate will be in the subject or object
position of that predicate at D-structure no matter where it is found at S-structure.
The principles that determine D-structure positions must therefore have something
to do with thematic relationships. We saw in chapter 1 how -roles are encoded in the
lexical entry of predicates. Yet in a sentence it is the arguments that are interpreted as
bearing these -roles. It must be the case therefore that these -roles are given from
the predicate to the argument. We can refer to this process as -role assignment. For
example:
theme
(65) a [an unexpected package] arrived
agent patient
b [Melanie] mended [the car]
The verb arrive is a one-place predicate, having one -role to assign which it assigns
to the argument an unexpected package in (65a). The verb mend is a two-place
predicate. It assigns the agent role to its subject and the patient role to its object.
Where can a predicate assign its -roles to? If there were no restrictions on this
then arguments would not have distributions at D-structure as they could appear
anywhere. We are assuming that this is not so and hence there must be conditions
which determine where -roles can be assigned. One fairly clear condition on -role