A shipwrecked cabin boy who invented political arithmetic and mapped Ireland
William Petty began as a teenage cabin boy whose captain beat him for missing a landmark he was too short-sighted to see. He ended up a knight, a founding member of the Royal Society, and the man who insisted that talk about a nation's wealth should rest on things you could count.
Petty was born in Romsey on 26 May 1623 to a family of clothiers. After breaking a leg at sea he was put ashore in Normandy, where he talked his way into a Jesuit college at Caen in Latin and paid his keep by teaching English. He came home fluent in several languages and versed in mathematics and astronomy, then studied medicine at Oxford after the royalist garrison there surrendered in 1646.
By 1651 he was teaching anatomy at Brasenose, and he made his name helping to revive Anne Greene, who had been hanged yet lived, and who won a pardon because people read her recovery as an act of God. Oddly, he was also Gresham Professor of Music in London throughout the 1650s. In 1652 he joined Cromwell's army in Ireland as its chief physician, and two years later won the contract to survey confiscated land so that the army's creditors could be paid in acres. The Down Survey, finished in 1656, earned him roughly 30,000 acres in Kenmare plus £9,000, and bribery accusations that dogged him until he died.
The Restoration barely dented him. At their first meeting Charles II waved away his apologies for serving Cromwell and chatted about ship design instead; Petty was knighted in 1661. He championed double-hulled boats, though one called the Experiment reached Porto in 1664 and then sank on the voyage home. Samuel Pepys was a friend, and a grandson described Petty's wife Elizabeth as the only person who could handle her tyrannical husband.
His lasting work was in economics. Having served as secretary to Thomas Hobbes and absorbed Francis Bacon's faith in measurement, he vowed to use only quantities, never vague comparisons, and called the result political arithmetic. His Treatise of Taxes and Contributions of 1662 favoured consumption taxes, condemned poll taxes and beer excise as hard on the poor, and argued that gold and silver made up under one percent of national wealth. He died in London on 16 December 1687 and was buried in Romsey Abbey.
Source: William Petty
