One of the great scientific philosophers of the 18th century, George Berkeley (1685-1753), was born at Castle Dysert near Thomastown. Berkeley’s most important contribution was on the nature of perception and existence and he influenced philosophers such as Kant, Locke and Descartes. He also engaged in a celebrated argument about Newton’s calculus and dividing by zero. Berkeley study divinity at TCD where, in an early experiment, he persuaded a friend to hang him until he was nearly senseless. In 1709, he published A New Theory of Vision that won him international praise. He left for England and the continent in 1713, returning for a while in 1724 as the Dean of Derry, and, in 1734, as Anglican Bishop of Cloyne in Cork.
Berkeley found the philosophical school of Immaterialism. The mind was for him the ultimate reality and he viewed even intangible ideas as part of the real world. He saw time as succession of ideas in a person’s mind, and his great principal was esse est percipi (‘to be is to be perceived’) put another way: things that cannot be perceived cannot exist. Berkeley believed his theories proved the existence of God, but his ideas were often controversial.
A debate raged between his Immaterialists and the opposing Materialists, who believed that anything that exists, including ideas, must have some physical basis or cause. Berkeley, criticised by some as illogical, fought back in A Discourse Addressed to an Infidel Mathematician (1734), arguing that Newton’s new calculus was also illogical: Newton’s technique involved dividing by infinitesimal amounts, but Berkeley argued that, since infinitesimals could not be perceived, they could not exist.
In the 1720s, despairing of the Old World’s decadence, Berkeley hopes for a new golden age in the Americas. He campaigned for a university there to educate colonist and native alike, and the government promised him £20,000. He moved his family to Rhode Island, but the money never arrived and, in 1731, they returned. Three years later, Berkeley move to Cloyne, where for 20 years he proved a charitable bishop, donating rent from the demense to help the poor. His last book, Sirirs (1744), advocates are drinking tar water – which he had seen used in America – as a panacea, and especially to treat dysentery. He died at Oxford and 1753.