6.2.3 Tense and Agreement
This analysis suggests that elements can move around in a structure quite freely and in particular both upward and downward movements are possible. But all the movements we have seen so far have been in an upward direction, including all the verb movements and the movement of the subject out of its original VP-internal position. It is possible that this might just be a bias of the small number of movement processes we happen to have reviewed so far. But it turns out, once one starts to investigate movements on a greater scale that the vast majority of them have an upward orientation, which might lead us to the conclusion that perhaps it is our analysis of the small number of apparent cases of downward movements that is at fault. One reason to believe that downward movements are not possible is that it is ungrammatical for certain things to move downwards, which is difficult to explain if such movements are allowable. For example, the verb always moves to the light verb positions and light verbs never move to the verb: