Prior to that he was an Assistant Professor of Philosophy at New York University. He holds a PhD in philosophy from the Massachusetts Institute of Technology. He works mostly in the philosophy of language, on descriptive and foundational issues in natural language semantics. Lately his work has borrowed ideas from formal epistemology and from metaethical expressivism to develop accounts of the meaning of epistemic and deontic modals, probability operators, conditionals, attitude verbs, and the language of spatial orientation. He also has research interests in metaphysics, on questions about the nature of modality, information, and randomness.