Raising and Control(39) evidently *(it) seems that the electrician found a mouse
The verb seem is one which takes a clausal complement but it has no thematic subject.
In this case the subject position is filled by a meaningless it, known as a pleonastic
subject. This subject, like all subjects in English finite clauses is obligatory. This
suggests that the obligatory nature of the subject is more than a semantic condition that
arguments need to be realised. In fact there seems to be a grammatical requirement that
clauses have subjects. This condition has been called the Extended Projection
Principle (EPP). Recall from chapter 3 that the Projection Principle ensures that the
lexical properties of heads are projected into the structure at all levels of syntactic
representation. Thus if a verb requires an object as a lexical property, it must have an
object at D-structure and at S-structure. The Extended Projection Principle claims not
only this, but that the subject position must be present at all levels of structural
representation and moreover that it must be filled by something at S-structure. Of
course, under usual circumstances there will be something in the subject position at S-
structure as an argument of the verb will move there for Case reasons. But even if
there is no argument inside the VP in need of Case, the subject position must be filled
by the insertion of a pleonastic subject:
(40) D-structure: [IP e may appear [that he left]]
S-structure: [IP it may appear [that he left]]
But non-finite clauses are different as they do not always have subjects:(41) a he appears [- to have left]
b they want [- to leave]
c [- to leave now] would be rude
How are these clauses able to escape the EPP? Note that it would in fact be
ungrammatical to fill these positions with a pleonastic subject:
(42) a he appears [it to have left]
b they want [it to leave] (with it being non-referential)
c *[it to leave now] would be rude
Recall also that the -Criterion requires that -roles be assigned to arguments.
While some verbs may take implicit arguments which are not actually present in the
structure but are ‘understood’ at a semantic level, these arguments are always
complements and never subjects:
(43) a he is eating a sandwich
b he is eating
c *is eating a sandwich
How are the non-finite clauses in (41) able to satisfy the -Criterion if there is no
subject to assign the -role to?
The answer to all these problems is that the non-finite clauses in question do not
lack subjects at all, they simply do not have pronounced subjects. One argument in
favour of this assumption is that in different non-finite clauses there may be different
types of unpronounced subjects. The argument is that one absent subject ought to be
exactly the same as another absent subject and only if they are present could they