Government and Binding Theory/Control Theory

Many chapters ago, we mentioned the Extended Projection Principle, which requires all clauses to contain subjects. However, this leads to a problem: Are most non-finite clauses exempt?

(1a) I want [you to study hard]. (1b) I want [IP to study hard]. (1c) [IP Calling me an idiot] is not a means of constructive discussion.

In (1a), to study hard had the subject you. In (1b) and (1c), however, to study hard and calling me an idiot lacked subjects. Are they exempt from the EPP?

The answer is 'no' because in GB Theory, linguists believe that PRO exists. It is a null subject, i.e. it is not phonetically realised.

Different subjects
We know that the subcategorisation frame and theta grid of reserve look something like this:

reserve [__ DP (PPfor)] < agent, patient, receiver>

Refer to the following:

(2a) It was nice of you [IP to reserve a seat for me]. (2b) He tried [IP to reserve a seat for me].

In (2a), it was clear that the agent was you, while in (2b), it was clear that the agent was he. This hints that there's a non-phonetically-realised subject that acts as the subject of the IP.

Plurality
Refer to the following:

(3a) They always compliment one another. (3b) *I always compliment one another. (3c) It is silly to compliment one another.

As we can see from (3a) and (3b), the reciprocal pronoun one another only appears in the complement position of a verb when the subject is plural. To account for the grammaticality of (3c), a null subject is needed.

Here is another example if you are not thoroughly convinced:

(3a) He always compliments himself. (3b) *They always compliment himself. (3c) It is silly to compliment himself.

Predicative APs
A predicative adjective modifies the subject, but is the complement of the verb:

(3a) I am growing old. (3b) The joke is growing old. (3c) [IP To grow old] is to gain experience.

In (3a), old modifies I. In (3b), old modifies the joke. How about (3c)? How is it possible that we have a predicative adjective, and yet there is no phonetically realised subject. This is another piece of evidence supporting the existence of PRO.

PRO theorem
PRO can only appear in subject positions of non-finite clauses. You cannot use it anywhere else:

(4a) *I think PRO has not done much good. (4b) *He cannot relate to PRO. (4c) *Don't give him PRO.

Is there anything that the subject of finite clause, the VP complement and the PP complement have in common...? Think about this before you read the theorem below.

PRO may only appear in ungoverned positions.

Yes, the explanation is that simple!

Wait... There's something wrong with this. Doesn't the higher IP govern PRO? Okay, let's modify our analysis a bit:

The significance of the PRO theorem will be even clearer in the next chapter.

Types of control
So far, we've postulated the existence of PRO and certain properties thereof, but we haven't really got started on how PRO is determined. This is the role of control theory.

Subject control and object control
Consider the following sets of sentences:

(5a) I want [IP you to do lots of homework]. (5b) I convinced you [IP PRO to do lots of homework]. (5c) I told you [IP PRO to do lots of homework].

(6a) I promise you [IP PRO to do lots of homework]. (6b) I am willing [IP PRO to do lots of homework]. (6c) I decided [IP PRO to do lots of homework].

In (5), PRO refers to the object you, while in (6), PRO refers to the subject I. Subject control occurs in (5), and object control in (6):

(5a) I want [IP you to do lots of homework]. (5b) I convinced youi [IP PROi to do lots of homework]. (5c) I told youi [IP PROi to do lots of homework].

(6a) Ii promise you [IP PROi to do lots of homework]. (6b) Ii am willing [IP PROi to do lots of homework]. (6c) Ii decided [IP PROi to do lots of homework].

Arbitrary control
Refer to the following example:

(7a) [IP PRO to be or PRO not to be] is the question.

It is hard to tell who PRO is. It could, in fact, be anyone. This is arbitrary control.

Obligatory control and optional control
Sometimes, it is not entirely clear whether a verb has subject or arbitrary control. Refer to the following examples:

(8a) I asked him how [IP PRO to study linguistics]. (8b) He thinks it's proper [IP PRO to call a teacher by his first name].

In (8), PRO can be both I or anyone. This is called optional control. We can demonstrate this by rewriting the sentences after Huang (1989) (it will be obvious in the next chapter why we used reflexives):

(9a) I asked him how [IP PRO to behave myself/oneself]. (9b) I think it's improper [IP PRO to make a fool out of myself/oneself].

This is not true of other sentences, as we can see by rewriting (5) and (6):

(10a) I want [IP you to behave yourself/*oneself]. (10b) I convinced you [IP to behave yourself/*oneself]. (10c) I told you [IP PRO to behave yourself/*oneself].

(11a) I promise you [IP PRO to do lots of homework]. (11b) I am willing [IP PRO to do lots of homework]. (11c) I decided [IP PRO to do lots of homework].

This is called obligatory control.

c-command
Is there a pattern here? Some linguists, specifically Williams (1980), suggests that obligatory control occurs if the controller c-commands PRO.

This is demonstrated by the following examples:

(12a) I want to be happy. (12b) I told him to be quiet. (12c) To smile nicely is good. (12d) To present him is my honour.

PRO traces
We wrap up the chapter by looking at the idea that PRO can move away and leave traces. Consider the following example:

(13) All he wants is PROi to be loved ti.

Here, PRO moved from object position to the subject of the non-finite clause in an A-movement.