I am primarily interested in what follows from what, and why. Hence my specialization in logic and the philosophy of logic. I have worked in areas from inductive to deontic logic, but the concept of necessity and the role it plays in grounding the relation of logical consequence have long been major interests. My work on validity in intensional languages reflects these interests, as does my ongoing investigation of the relations between formally precise and intuitively correct accounts of logical consequence. This latter work grows out of the observation that the informal characterization logicians give of the logical consequence relation does not always square with the almost universally accepted model-theoretical definition of this relation. Issues about the role of necessity, what is to count as a logical constant, the correct way of representing logical form, and the relation of set theory to logic all come into play. A related question I have investigated is whether there can be genuine, as opposed to merely verbal, disputes about which principles of logic are correct. (This is the problem of deviant logics or logical pluralism.) In my paper on deviance I try to show how genuine disagreement about logic could come about. Another matter that interests me is the relation between natural and formal languages. One of my papers explores the logic of English indicative conditionals, while another shows that certain non-trivial fragments of English can be translated into the language of propositional logic in a completely mechanical way.