Richard Price

Richard Price (1723-1791) was a Welsh Dissenting minister, moral philosopher and mathematician who spent most of his adult life in London. He belonged to the tradition of Dissenters, Protestants who had broken with the Church of England, and he is remembered today above all for his role in publishing the theorem that bears Thomas Bayes's name, though his work also ranged across ethics, population, finance and politics.

He was born in Llangeinor, in Wales, and moved to London as a young man after his father's death. There he studied at a Dissenting academy in Moorfields, where he became close to Thomas Bayes. After Bayes died in 1761, Price found among his papers an essay on probability and sent it to the Royal Society, which published it in 1763. The paper contains the formula now called Bayes's theorem, though it is the name of the mathematician who died first that became attached to it.

In moral philosophy, his Review of the Principal Questions in Morals argued that good and evil are discerned by reason rather than by feeling alone. In his debate with Joseph Priestley he defended human free agency and the immateriality of the soul. His political writings, above all Observations on the Nature of Civil Liberty (1776), supported the American colonists, sold in enormous numbers and made him one of the best-known men in England. He also wrote on public debt, population and slavery, and welcomed the French Revolution.

His circle included Mary Wollstonecraft, who attended his congregation at Newington Green, and his ideas on equality and reason fed the political debates of his day. Today he is studied both as a forerunner of modern statistics and as a defender of civil liberty.