Gabriel is an M+E generalist with a home base in the metaphysics of mind. He works on a wide variety of topics in philosophy of mind, metaphysics, philosophy of language, and philosophy of mathematics. He has worked on on consciousness, the knowledge argument, physicalism, modality, grounding, semantics for mathematical terms, semantic externalism, twin-earth, analog representation, the scope of a priori knowledge, and on what it is to possess and master a concept.