188.8.131.52 D-structure and Theta Theory
We have now reviewed three simple and basic principles which regulate the assignment of Θ-roles within a structure: the Locality Condition on Theta-role Assignment, the UTAH and the Theta Criterion. All of these apply to D-structures, restricting the distribution of arguments at this level of representation. Collectively, the principles which govern Θ-role assignment are often referred to as Theta Theory and this can be considered as a part of the grammar, similar to the principles of X-bar theory which regulate the general formation of structures. A final important contributor to the well-formedness conditions of D-structure is the lexicon which provides structures with categorial information and Theta theory with the Θ-roles to be assigned. We might represent this in the following way:
One might wonder if adjunction conforms to structure preservation as it does seem to alter the structure from its D-structure condition. However, it should be noted that adjunction does not alter lexically determined aspects of structure and so is perfectly compliant with the Projection Principle which supersedes structural preservation. Moreover, adjunction is something which X-bar theory allows for and hence to create an adjunction structure is not to create something that violates the possible X-bar nature of the structure. In this way, adjunction movement does not radically alter structure and can be seen as structure preserving.
4.2.2 The Specifier of the DP
If X-bar theory is correct however, this observation cannot be taken to show what it seems to: i.e. that the specifier and the determiner sit in the same structural position. Words and phrases cannot be in complementary distribution as they cannot appear in the same positions in a phrase. Some other element must appear in complementary distribution with the determiner in (39c), not the possessor. But what?
Chapter5 Verb Phrases
The principles of Theta Theory introduced in chapter 2 will play a large part in determining the structure of the VP, alongside those of X-bar theory. In particular we will be guided by the Uniform Theta-role Assignment Hypothesis (UTAH), which as we explained in chapter 2 assumes that specific Θ-roles are assigned to similar positions in all structures. Thus, if we find evidence that a particular Θ-role, theme for example, is assigned to a particular position in one structure, then by the UTAH we should assume that it is assigned to this position in all structures where it is found. In many ways this is a very simple theory, but it does lead to the assumption of somewhat more abstract structures than might have been guessed at prior to analysis. However, we will demonstrate that the more abstract structures have quite a few advantages over what might at first seem to be more straightforward analyses and these advantages can be used to independently motivate the analyses and thus support the assumption of the UTAH. We will start our discussion with the simpler cases and work our way to the more complex ones, though this order of presentation might not be the usual one we find in grammar books.
There looks to be a good deal of freedom in determining the position of the adverb and thus it appears to be able to adjoin to virtually any part of the VP. The one exception is that the adverb may not intervene between the verb and its object. However, the adjacency requirement between the verb and its object is not so straightforward to account for under the assumptions we have been making. Other accounts of this restriction have made different assumptions. For example, Radford (1988) assumes that the object is in the complement position of the verb and that the adjacency requirement between the two is a reflex of X-bar theory itself: the head must be adjacent to its complement otherwise an ill formed structure results:
6.1 The structure of IP
To see the advantage of this analysis, consider what happens if we do not assume that the inflectional element is the head of the clause. English is often described as an SVO language, based on a way of classifying languages in accordance with the ‘typical’ ordering of the major elements of the sentence (subject, verb and object). Without X-bar theory and the notions of head, complement and specifier, however, this is just a description of the facts which tells us nothing beyond what can already be observed. Assuming X-bar theory we have a way of accounting for word order patterns by using general statements about the relationships between elements in an X-bar structure and so this is a step in the right direction. However, if we do not assume that the inflection is a head, it is not easy to think of how we can use X-bar generalisations to account for the basic word order of English. This is especially so if we take the traditional view that sentences are exocentric and therefore stand outside of the set of facts that X-bar theory can account for. Only if we assume that sentences are endocentric can X-bar generalisations be used to account for word order facts concerning sentences.
7.3.5 Subject questions
To conclude this section. It seems that the distribution of elements in an English sentence is partly due to structural conditions imposed by X-bar theory and the selectional requirements of certain heads, partly due to the morphological properties of certain heads and partly due to general ordering requirements affecting certain elements. Specifically we have seen the effects of the following conditions: