Syntactic Theory

Constraints on Wh-movement

1.Movement and Locality

Wh-movement is local: a wh-phrase has to move through the specifier of each CP it crosses.

Let us explain it in two stages to see it clearly.

1. The wh-phrase moves to a local [Spec, CP], the [Spec, CP] of the clause which contains it.

2. Each following step is also local in that the wh-phrase moves to the next [Spec, CP] up.

Wh-movement cannot skip a [Spec, CP] to move to a higher one.

Let us have look at the case:

In A1), a wh-phrase is extracted from the lower clause and the embedded [Spec, CP] remains unoccupied. We propose that the wh-phrase transits through this unoccupied [Spec, CP] position on its way to the highest or root [Spec, CP], case A2).

While a wh-phrase can be separated from its base-position by intervening occurrence of the complementizer that, the intervention of interrogative constituents such as whether, whom or when renders the sentence at the best marginal and sometimes ungrammatical.

Thus, the stepwise movement is possible in case A but it is not possible in case B because whether occupies the intervening specifier position.

Now let us move on to the second point.

We cannot move two constituents to the specifier of the same clause, which means, there is only one position through which a wh-phrase can escape from the clause which contains it to move into a higher clause.

Following case shows this point clearly:

c) To whom did he say what?
d)*To whom what did he say?
e)*What to whom did he say?

We could draw the conclusion schematically. A wh-phrase moves first into the specifier of the clause that dominates it, and then it moves step by stp to the higher specifiers.


Extracting the subject

  • There are locality conditions on movement: a wh-constituent cannot cross another wh-constituent in the specifier of CP or the interrogative C if.

  • There is a subject/object asymmetry: while objects can be extracted across a complementizer of the clause which immediately contains their base-position, subjects cannot cross the overt complementizer which introduces the clause that immediately contains them.

Let us have a look at the case to explain it:

a) is ungrammatical because the extraction of a subject wh-phrase is blocked whenever it has to cross an element in the adjacent [Spec, CP] or in the adjacent C.

b) is ungrammatical. The subject is moved out of its base-position into the specifier of the CP of a higher clause. The complementizer of the lower clause must be non-overt. Objects can be extracted across a complementizer but subjects cannot be extracted across an adjacent that.


a)*I asked them [cp whoi [ip they wonder [cp whether
 [ip ti will invite Mary]]]].
b)*I wonder [cp whoi [ip they think [cp ti
 that [ip ti will invite them]]]].

Adjunct extraction

Subject/object asymmetry: objects can marginally cross a wh-phrase, but subjects must not be extracted across an adjacent wh-phrase.

adjunct/object asymmetry: objects can marginally cross a wh-phrase, adjuncts cannot.


c) whyi did you say [cp that [ip they will invite me ti]]
d)*whyi do you wonder[cp whether [ip they told
 me [cp ti that [ip he would invite her ti ]]]]
e)*whyi do you wonder ti [cp whether [ip they
 told me [cp that [ip he would invite her ]]]]

In c) the adjunct crosses that, come complementizer of the clause containing the base-position of why, it is grammatical.

In d) the adjunct crosses whether, which is in the [Spec, CP] of a higher clause, it is ungrammatical.

In e) as indicated by the trace, why originnates in the matrix clause.

Excersice for Constrains on Wh-movement

Please press here to start the next step: Wh-movement in the Relative Clause