George Berkeley

George Berkeley (/ˈbɑːrkli/ BARK-lee; 12 March 1685 – 14 January 1753), known as Bishop Berkeley (Bishop of Cloyne of the Anglican Church of Ireland), was an Anglo-Irish philosopher, writer, and clergyman who is regarded as the founder of "immaterialism", a philosophical theory he developed which was later referred to as "subjective idealism" by others. As a leading figure in the empiricism movement, he was one of the most cited philosophers of 18th-century Europe, and his works had a profound influence on the views of other thinkers, especially Immanuel Kant and David Hume. Interest in his ideas increased significantly in the United States during the early 19th century, and as a result, the University of California, Berkeley, as well as the city of Berkeley, California, were both named after him.

In 1709, Berkeley published his first major work An Essay Towards a New Theory of Vision, in which he discussed the limitations of human vision and advanced the theory that the proper objects of sight are not material objects, but light and colour. This foreshadowed his most well-known philosophical work A Treatise Concerning the Principles of Human Knowledge, published in 1710, which, after its poor reception, he rewrote in dialogue form and published under the title Three Dialogues Between Hylas and Philonous in 1713. In this book, Berkeley's views were represented by Philonous (Greek: "lover of mind"), while Hylas ("hyle", Greek: "matter") embodies Berkeley's opponents, in particular John Locke.

Berkeley argued against Isaac Newton's doctrine of absolute space, time and motion in De Motu (On Motion), first published in 1721. His arguments were a notable precursor to those of Ernst Mach and Albert Einstein. In 1732, he published Alciphron, a Christian apologetic against the free-thinkers, and in 1734, he published The Analyst, a critique of the foundations of calculus, which was influential in the development of mathematics. In his work on immaterialism, Berkeley's theory denies the existence of material substance and instead contends that familiar objects like tables and chairs are ideas perceived by the mind 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.

Interest in Berkeley's work increased greatly after World War II because he tackled many of the issues of paramount interest to philosophy in the 20th century, such as the problems of perception, the difference between primary and secondary qualities, and the importance of language.