Basic English Syntax with Exercises

Null Case

8.2.2 Control

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 (1989) 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).

8.2.2 Control

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.

8.3 The Gerund

However, such gerunds are standardly assumed to have PRO subjects and hence the subject position is not empty and we can account for why the determiner is impossible. In such gerunds we might suppose that the ing morpheme is added to the structure quite high, perhaps above the tense element. If we further assume that it is a non-finite tense which is responsible for assigning the Null Case borne by PRO we can account for why it is possible to have a PRO subject in a gerund.