In this chapter, we have so far covered some of the core concepts in syntactic theory, and seen how we can use them to reason about grammatical structures and relationships between classes of sentences.
These core concepts include the observation that natural languages are better described in terms of structural relations rather than just the linear order of words, that the properties of a phrase are determined by its head, and that we can use grammaticality judgements to investigate fine details about a language’s syntax. We’ve also seen how we can usefully describe the properties of certain classes of clauses (questions and passives) by showing how they are systematically related to other clauses (statements and actives), and how these concepts can give us a handle on syntactic differences across languages. As just one example, the head direction parameter accounts for differences in word order between English and Japanese in all types of clauses.
Even though we have mostly focused on one language, we have still only scratched the surface of the language’s syntactic grammar. However, we now have tools we could apply either to other phenomena in English, or to the grammar of entirely unrelated languages.
In the remaining sections of this chapter we introduce a particular formal notation used to represent the syntactic structure of natural language: tree diagrams. In particular, we will introduce a derivational implementation of X-bar theory, where the grammatical sentences of a language are described in terms of constraints on a set of well-formed tree structures, and movement transformations that can be applied to those tree structures.