8.2 Raising and Control
Consider the two sentences in (44). They both appear to have missing subjects and in other ways they seem to be similar. However, even at this point we can see that the two missing subjects are not entirely equivalent. In (44a), the missing subject is referentially identical to the subject of the higher clause, Tim. This subject is not semantically related to the verb of its own clause: Tim is not the one doing the seeming. We have already seen that verbs like seem do not have a subject of their own and often have pleonastic subjects, as we see in (45a). Thus the missing subject of the non-finite clause and the overt subject of the higher clause share a single Θ-role assigned from the lower predicate tall. In other words, they represent a single argument. This contrasts starkly with the situation in (44b), where the missing subject and the overt subject of the higher clause bare completely different Θ-roles: Robin is the thematic subject of want and the missing subject is the thematic subject of rich. The two subjects are coreferential, but they are independent elements in exactly the same way that a pronoun and its referent are independent elements: