Relative Clausesbecause the clause needs to be interpreted as interrogative. This clearly cannot be the
reason for the movement of the relative pronoun as relative clauses are not
interrogative. The reason why a relative pronoun moves is presumably something to do
with its function as a mediator between the modified noun and a position inside the
relative clause and again this seems to differ from the wh-interrogative as wh-elements
in interrogatives do not act as mediators.
However, if we take one step back from the details, we can see some striking
similarities between the reasons for wh-movement in both types of clauses. For one
thing, both movements have semantic rather than grammatical motivations. Moreover,
the reason why the wh-element moves in an interrogative is to enable the CP to be
interpreted as a question. The reason why the wh-element moves in a relative clause is
to enable the CP to be interpreted as a modifier.
Finally by moving to the specifier of the CP, the wh-element is interpreted as an
operator in both interrogative and relative clauses. The fact that one is interpreted more
like a quantificational operator, like quantificational pronouns such as everyone or
someone, while the other is interpreted like an anaphoric operator, which is
referentially dependent on some other element in the sentence, like a reflexive pronoun
such as himself, falls out due to the different functions of questions and relative
clauses: one asks a question and the other modifies a noun.
What about the use of empty operators in relatives as compared to their limited use
in interrogatives?:
(97) a the idea [Op 1 (that) I had t 1 ]
b *I asked [Op 1 (if) you had t 1 ]
Again this may be entirely due to differences in the use of these constructions. As a
relative clause modifies a noun making use of an anaphoric operator, there must be an
antecedent for the operator to take its reference from. This antecedent, i.e. the modified
noun, can provide us with the content of the operator and hence this is recoverable
even if we cannot see the operator itself. With a question, however, as there is no
antecedent, the content of the operator has to be visible on the operator itself and hence
the null operator cannot be used in this way. The null operator used in yes–no
questions is clearly non-referential and hence has no specific content to be recovered.
In this situation then the null operator can suffice.
In conclusion then, it seems that the differences between interrogative and relative
clauses are mainly to do with their different functions. Syntactic and other differences
may be derivable from these. Certainly, given the above discussion, it is not really
surprising that they have very similar internal organisations and employ very similar
processes in their formation.