George Berkeley (; 12 March 168514 January 1753) — known as
Bishop Berkeley (
Bishop of Cloyne) — was an
Anglo-Irish philosopher whose primary achievement was the advancement of a theory he called "immaterialism" (later referred to as "
subjective idealism" by others). This theory denies the existence of
material substance and instead contends that familiar objects like tables and chairs are only
ideas in the
minds of
perceivers, and as a result cannot exist without being perceived. Berkeley is also known for his critique of
abstraction, an important premise in his argument for immaterialism.