Chapter 7 - Complementiser PhrasesThe case of aspectual auxiliaries is similar to the modals. In the previous chapter
we claimed that these auxiliaries are inserted elements that may move from the tense
position to the I position when there is null agreement in I. Thus, if they are in I, they
can also undergo movement from I to C:
(41) CP
C'
C IP
DP I'
you I vP
- ∆ v'
v vP
have seen my father
Main verbs are problematic however, as they do not appear to be able to move to
the C position:
(42) a have you read the book?
b *read you the book
c did you read the book?
As we can see, a yes–no question involving a main verb moving to the C position is
ungrammatical and instead of the main verb moving to C what happens is that the
dummy auxiliary do is inserted into the tense position, and from there it moves to C,
via I. Of course, this is readily accounted for if main verbs do not move to I, as is the
standard assumption. If they are never in I they cannot move to C without violating the
head movement constraint. But we argued that main verbs can move to I and so it is
not readily apparent why they cannot move to C. We will put this issue to one side
until we have discussed the facts about I-to-C movement more fully. For the time
being, then, we will concentrate on I-to-C movement as it involves auxiliary verbs.
3.4 The interaction between wh-movement and inversion
The most important issue concerning I-to-C movement is why it happens. There are
two main views on this. One is that I-to-C movement happens because there is a bound
C morpheme in interrogative clauses and this triggers the movement of the auxiliary to
support it in the same way that inflections trigger verbs and auxiliaries to move. The
other view is that the movement happens in precisely the cases when there is nothing
in C and there is a requirement that there must be. The first is perhaps the most
intuitively obvious, but it faces a number of problems which make the other approach
more attractive. Let us consider each proposal separately.