Phrase structure and dependence

Syntactic structures have been analysed in terms of constituent hierarchies and also in terms of dependency relations. While these two traditions have sometimes been presented as competing with each other, there is no reason in principle why syntactic dependencies and constituent hierarchies should not both be part of the grammar, complementing each other. Indeed, within transformational grammar and more specifically within the Principles and Parameters theory, various dependencies are postulated alongside the basic constituent hierarchy analysis of sentences. The most salient of these are the various types of anaphoric dependencies, but other relations, like for example thematic, government or chain relations, have also from time to time been thought of as constituting dependencies. Within this framework it remains true however, that the basic structural organizing principles are couched in terms of constituent hierarchies, dependency relations are not taken to play a role here. In what follows I shall propose that dependency relations are more central to the grammar. I shall postulate a new module: dependency theory. The basic syntactic analysis of a sentence will not simply consist of a set of elements arranged in a constituent hierarchy. It will include also a dependency structure defined on these elements: all syntactic elements participate in both a hierarchical and a dependency structure. In section 1 of this paper I shall show that dependency theory makes it possible to radically simplify the theory of phrase structure. In section 2, I shall argue that the evidence that has standardly been taken to motivate binary rightward branching analyses is better treated in terms of dependency relations between constituents.