Complex sentence: His primary areas of research include the philosophy of language and the philosophy of logic; he also works in metaphysics, model theory, and the philosophy of mathematics, with an interest in the works of Gottlob Frege.
Split into simpler sentences: His primary areas of research include the philosophy of logic and the philosophy of language. He also works in metaphysics, model theory, and the philosophy of mathematics, with an interest in the works of Gottlob Frege.