I am primarily interested in the human capacity for syntax, the cognitive system that underlies the patterns found in the grammar of human languages. The core questions are: what creates the patterns? how do they relate to meaning on the one hand, and sound, on the other? What governs the range of variation in the patterns? Answering these questions allows us to tackle the issue of what the nature of the syntactic system is.
My new book LANGUAGE UNLIMITED explores some of these ideas in a way that's aimed at the general reader.
My other main interest is how theories of syntax can be used to handle the variable use of different syntactic patterns by a single individual, and whether these theories have anything to contribute to explaining probabilistic patterns we see in the use of different syntactic forms.