George Berkeley

George Berkeley (12 March 1685 – 14 January 1753), also known as Bishop Berkeley, was an Irish philosopher. He is best known for developing an early form of idealism, according to which the only things which exist are minds and the ideas which they perceive. The University of California, Berkeley, and the city that grew up around it were both named after him.

Contributions to philosophy

Berkeleyan idealism

The central thesis of Berkeley's idealism was that only minds and the ideas which they perceive exist. This committed him to immaterialism, the position that there are no material substances, where a substance is something which could exist even if nothing else did. According to Berkeley, objects like trees and chairs existed, but they could not exist independently of being perceived by a mind. He summarised this position with his famous dictum, "Esse est percipi" ("To be is to be perceived").

Berkeley and infinitesimals

In 1734 Bishop Berkeley published a tract called The Analyst. In this the new calculus of Newton and Leibniz was attacked and especially the concept of "fixed infinitesimal" set forth by Isaac Newton in the Principia and in an appendix to the Opticks. Since the concept of an infinitely small, and yet finite, quantity was still fairly muddled and confused, Berkeley, although not a mathematician by training, made an extremely effective attack. His arguments provoked controversy among mathematicians and led to the clarification of central ideas underlying the new theory.