Chapter 8 - The Syntax of Non-Finite ClausesHowever, this conclusion is problematic both conceptually and empirically. On
conceptual grounds, it is odd to say the least that there should be a principle stating
that all DPs must have Case and then to find out that there is one DP that not only does
this not apply to, but exactly the opposite holds of it and it cannot have Case. The
empirical issue is that the assumption does not account completely for the distribution
of PRO as there are places which are not Case marked, and so could not support an
overt DP, but in which PRO cannot appear either. One such place is the subject
position of the non-finite complement clause of a raising verb or a passive verb:
(73) a it seems [PRO to be rich]
b it was believed [PRO to have gone]
One possible solution to both these problems would be to claim that PRO doesn’t
avoid Case positions per se, but has to sit in special Case positions which up to now
have been assumed not to be Case-marked, but in fact might be assigned a special
Case, applicable only for PRO. Chomsky and Lasnik (1993) proposed that PRO must
sit in special Case marked positions. They argue that the subjects of certain non-finite
clauses are not Caseless but that what they term ‘Null Case’ is assigned to them. Only
PRO can bear Null Case and Null Case is the only Case that PRO can bear. Thus PRO
will not be able to sit where overt DPs go as these will be Case marked with something
other than Null Case. Moreover no overt DP can sit in a position in which it would be
assigned Null Case as this is not ‘strong’ enough to satisfy the Case Filter. The good
thing about this assumption is that it predicts complementary distribution between
overt DPs and PRO but does not force us to assume that PRO can occupy any position
in which we cannot find an overt DP. From this perspective, then, PRO cannot sit in a
position to which no Case is assigned, as in (73).
So far, I have remained uncommitted about the status of the clause that contains
PRO: is it a CP or is it an IP? Under both assumptions that PRO cannot sit in Case
positions or that it can only sit in Null Case positions we have to ensure that the place
where it can be found is not assigned a full Case from an element outside the clause.
We have seen that as PRO cannot be the subject of an exceptional clause it must be
assumed that this is not possible. One way to ensure that nothing else can assign Case
to the place occupied by PRO is to assume that it is protected by a CP. Recall that a
governor can govern up to a CP, but not through it as CP acts as a barrier to
government. For this reason then, we will assume that all clauses containing a PRO
subject are CPs and not IPs.
Turning to the referential properties of PRO we find that this is quite complex. To
see how PRO behaves, we should first consider how other pronouns behave in terms of
reference. There are two types of referential pronouns which behave differently with
respect to each other. Compare the following:
(74) a Sue said Lucy likes her
b Sue said Lucy likes herself
In (74a) the pronoun her can either be taken as referring to Sue or someone not even
mentioned in the sentence. Note that it couldn’t possibly refer to Lucy. In contrast the
pronoun in (74b) can only refer to Lucy and cannot refer to someone not mentioned or
to Sue. We call the first kind of pronoun a pronominal and the second kind anaphors.