His thought continues to have a major influence in contemporary thought, especially the fields of metaphysics, epistemology, ethics, political philosophy, and aesthetics.
He attacked surmise and unexamined premises wherever he found them, and his skepticism pointed out metaphysics in areas that other empiricists had assumed were material.
Before modern science, representation was naturally contingent and the universal aspirations of science (metaphysics) were bound to the nature of the epistemological ground ("arch").
His main areas of research include philosophy of language, philosophical methodology and related areas in epistemology, philosophy of mind, and metaphysics.