William Petty

Sir William Petty (26 May 1623 – 16 December 1687) was an English economist, physician, scientist and philosopher. He first became prominent serving Oliver Cromwell and the Commonwealth in Ireland. He developed efficient methods to survey the land that was to be confiscated and given to Cromwell's soldiers. He also remained a significant figure under King Charles II and King James II, as did many others who had served Cromwell. Petty was also a scientist, inventor, and merchant, a charter member of the Royal Society, and briefly a member of the Parliament of England. However, he is best remembered for his theories on economics and his methods of political arithmetic. He was knighted in 1661.

Early life

Petty was born in Romsey, where his father and grandfather were clothiers. He was a precocious and intelligent youth and in 1637 became a cabin boy. His readiness to provide caricatures of fellow crew members won him few friends. He also learnt of his defective sight when he failed to spot a landmark he had been told to look for. The captain, who had by this time seen the landmark from the deck for himself "drubbed him with a cord". He was subsequently set ashore in Normandy after breaking his leg on board. After this setback, he applied in Latin to study with the Jesuits in Caen, supporting himself by teaching English. After a year, he returned to England, and had by now a thorough knowledge of Latin, Greek, French, mathematics, and astronomy.

At Oxford

After the Third Siege of Oxford had resulted in the garrison surrendering to the parliamentarians on 24 June 1646, Petty arrived in the town and was offered a fellowship at Brasenose College and studied medicine at the University. He befriended Hartlib and Boyle and became a member of the Oxford Philosophical Club.