188.8.131.52 Unaccusatives and ergatives
The intended interpretation of (70b) is that Rob pretends to be rich in order to impress the neighbours, an thus it is the ‘seeming’ rather than the ‘being rich’ that is being modified by the purpose clause. The ungrammaticality of this sentence with this interpretation demonstrates that expletive it is unable to license this kind of modifier. When the thematic subject is raised, however, the purpose clause is grammatical. The quasi-argument weather predicate it appears to behave like a thematic argument in this respect as it does license a purpose clause. Obviously I do not want to claim that the there subject in there constructions is the same thing as a weather predicate’s quasi-argument subject.