ABSTRACT
It is a truth universally acknowledged (well, almost) that the surface subjects of the following sentences are not 'really' subject of the higher verb:
[1] Tim appeared to shun publicity.
[2]
(a) Max seems to own a number of houses.
(b) A number of houses seem to be owned by Max.
[3] There happened to be understudies available.
In [1] it is not 'Tim' who 'appeared'. What 'appeared', surely, is that 'Tim shunned publicity'. Tim is an argument only of shun, not of appear. Similarly, the equivalence in truth-value of sentences [2](a,b) is explained if we assume that seem is here a one- place verb whose sole argument is roughly the clause Max owns a number of houses. The difference between the sentences depends on whether or not that embedded clause has been passivised, but seem itself is indifferent as to which NP winds up as its subject. Assuming a similar argument structure for happen and an embedded clause there were understudies available explains the possibility of a dummy surface subject there in [3]. Dummy there cannot be an argument. Its presence is licensed - or not, as in [4] - by the lower clause rather than by happen:[4] *There happened to find understudies available.
[5] The director happened to find understudies available.
(Example [5] shows that [4] is not ruled out simply because of some incompatibility between happen and find.)