Government and Binding Theory/Subjacency

Despite what we've seen last time, movement is not unrestricted. It is not always possible to move anything anywhere. Consider this example:

(1a) You did do what? ⇒ What did you do?
(1b) John did think you did what? ⇒ What did John think you do?
(1c) John asked if Mary thought I had really stolen what? ⇒ *What did John ask if Mary thought I had really stolen?

This shows that there seems to be restrictions on how far elements can move, leading to bounding theory.

Subjacency

Although movement is clearly restricted, it is often hard to pinpoint on a specific node that prevents movement. As we have seen above, moving a wh-element to the front is grammatical across one phrase, but not across two. Subjacency is a proposed principle that explains why movements of certain lengths cannot occur.

Subjacency Principle Movements can cross a maximum of one bounding node.

What counts as a bounding node is parameterised across languages. Consider this ungrammatical example:

(2a) [CP [IP   —     —  [IP John did2 ask [CP if Mary thought [CP [IP I had really stolen what1]]]]?
(2b) [CP [IP What1 did2 [IP John  t2  ask [CP if Mary thought [CP [IP I had really stolen  t1  ]]]]?

In our example, what₁ must have jumped across two bounding nodes, which is unacceptable. The question remains: Is the bounding node CP or IP? We can consider these two examples, one of an interrogative and one of a relative clause:

(3a) [CP   —     —  [IP John did2 ask [CP if [IP I had really stolen what1]]]]?
(3b) [CP What1 did2 [IP John  t2  ask [CP if [IP I had really stolen  t1  ]]]]?
(3c) [CP          —          [IP I wonder [CP whether [IP it is impossible [IP PRO to judge [DP whose ability]1]]]]
(3d) [CP [DP whose ability]1 [IP I wonder [CP whether [IP it is impossible [IP PRO to judge        t1          ]]]]]

Here, there was only one CP node crossed, but multiple IP nodes. The resulting sentence is wrong. Clearly, IP, not CP, matters.

However, note that sometimes multiple movements occur. In this case, as long as each movement only hops across one bounding node, the sentence is fine:

(4a) [CP   —     —  [IP Mary did2 think [CP    —  that  [IP I had really stolen what1]]]]?
(4b) [CP   —     —  [IP Mary did2 think [CP what1 that  [IP I had really stolen  t1  ]]]]?
(4c) [CP What1 did2 [IP Mary  t2  think [CP   t1   that  [IP I had really stolen  t1  ]]]]?

Note that what first moves to the specifier position of the CP it's in, crossing one IP node on the way. Then it moves to the specifier position of the greater CP, leaving a trace in the original CP and again crossing an IP node.

IPs are not the only bounding nodes in English. DP exhibits similar properties.

(5a) [CP   —   —   [IP you do2 disagree [PP with [DP the criticism [PP of [DP John's discovery of what1]]]]]]
(5b) [CP   —   —   [IP you  t2 disagree [PP with [DP the criticism [PP of [DP John's discovery of  t1  ]]]]]]
(5c) [CP What1 do2 [IP you  t2 disagree [PP with [DP the criticism [PP of [DP John's discovery of  t1  ]]]]]]

It is thus said that IPs and DPs are the bounding nodes of English.