Petty, William

views updated May 18 2018


(b. Romsey, Hampshire, England, 26 May 1623; d. London, England, 16 December 1687)

economics, demography, geography.

Petty was a prominent virtuoso in an age of the many-sided genius. His investigations ranged over anatomy, geodesy, the design of ships, and the application of mathematics to diverse natural and practical problems. His major contributions were in what he called “political arithmetic.”

Petty was the eldest surviving child of Anthony Petty, a cloth worker and tailor who owned his home and probably some farm land, and Francesca Denby Petty. Petty’s chief childhood amusement, he later told John Aubrey, was“looking on the artificiers, e.g. smyths, the watchmakers, carpenters, joiners, etc.” After the usual education in Latin, Greek, and arithmetic, he became at the age of thirteen a cabin boy on a merchant ship. He studied navigation while aboard, although he was extremely nearsighted. After ten months at sea he broke his leg and was set ashore near Caen.

There he impressed the Jesuit fathers, who admitted him to their college. More than a year later he returned to England and joined the navy. He left after the outbreak of civil war but always retained an interest in ships and the sea. In 1643 Petty went to the Netherlands to study medicine at Utrecht, Leiden, and Amsterdam. In 1645 he continued on to Paris and studied anatomy with Hobbes, who introduced him to Mersenne and his famous circle of friends who studied natural philosophy.

In 1646 Petty returned to England and met Samuel Hartlib, who persuaded Petty to write a tract on education. The result was The Advice of W.P to Mr.S. Hartlib for the Advancement of Some Particular Parts of Learning (1648). Following Bacon’s teachings, Petty recommended the establishment of a college” for the advancement of all mechanical arts and manufactures” where practical and theoretical questions would be investigated and a history of the trades would be written.

Petty resumed his anatomical studies, and by 1649 he was at Oxford University. In that year John Wilkins and other members of the university formed a club for experimental philosphy, which was an antenedent to the Royal Society of London. Because of the proximity to an apothecary shop, the club soon began holding its meetings in Petty’s lodgings.

Petty’s professional standing advanced rapidly. In 1650 he received the doctorate of physic from Oxford and became a candidate at the College of Physicians in London. He was soon appointed professor of anatomy and vice-principal of Brasenose College, Oxford, and then professor of music at Gresham College, London.

Nevertheless, in 1652 he left these positions to become physician-general to Cromwell’s army in Ireland. Having found it necessary to pay the troops with land from the defeated Irish, Cromwell needed a land survey. The appointed supervisor proved inept,. and in 1655 Petty volunteered to carry out the survey in thirteen months. His proposal was accepted, and he engaged about a thousand men for the task. In March 1656 he completed the survey as scheduled. Although it was an outstanding achievement, there were errors of underestimation of 10–15 percent, which correspondingly lessened his pay.

As a supplement to the Down Survey, Petty also undertook the complete mapping of Ireland. A general map and thirty-five county and barony maps were printed around 1685—the most detailed maps ever published for a whole country. Even more detailed maps, some of which have since been destroyed by fire, remained unpublished. Another supplement to the survey was the first census of Ireland, which was taken around 1659; the extent of Petty’s involvement is unknown. The only copy of the results was among his papers, but he never made use of it in his writings.

Petty’s payment for his survey enabled him to buy cheaply forfeited and mortgaged lands, thus acquiring considerable property, which he continued to augment throughout his life. Having acquired his wealth from other men’s misfortunes, Petty endured hostility and litigatioin for the rest of his life.

Petty abandoned the practice of medicine and henceforth devoted a major part of his time and thought to managing his property. He was a friend of the Cromwells, both before and after the collapse the Cromwells, both before and after the collapse of the Commonwealth; but he acquiesced in the Restoration, and Charles II knighted him in April 1661. Petty aspired to, but never received an important government office. One-of his hopes was to be placed in charge of an Irish statistical office. He was also on good terms with James II, although disappointed in his support of the Irish Catholics.

In 1667 Petty married Elizabeth Fenton, the attractive and intelligent widow of Sir Maurice Fenton. She was the daughter of Sir Hardress Waller, a prominent Irish Protestant, who had provided strong support for Petty’s land survey. Two sons and a daughter survived infancy. Although Petty twice declined a baronetcy, James II made his widow Baronness Shelburn in 1688.

By the end of 1659 Petty had returned from Ireland to London, where he rejoined those members of the philosophical club who had moved back from Oxford and had begun meeting at Gresham College. When this group became incorporated in 1662 as the Royal Society of London for Promoting Natural Knowledge, Petty was a charter member of its council. In 1673 he was elected vice-president. His interest in the society never waned, but his participation was curtailed by his becoming nearly blind in 1670 and by his being in Ireland managing his property from 1666 to 1673 and from 1676 to 1685.

A throughgoing Baconian, Petty emphasized the collection of information and the practical application of scientific principles and knowledge. Before the Royal Society he read instructions concerning the technical processes that were involved in his father’s trade of cloth making and dyeing. In a discourse read before the Royal Society in 1674, he expressed interests in the physical sciences that were typical for his time. He urged the study of number, weight, and measurement; and he provided diverse examples, such as the relationship between scale and strength of structures; calculations of the distance that sounds, odors and light travel in relatioin to the magnitude of the source; and formulas to predict prices and human longevity. He also suggested an explanation of elasticity and antomic theory of matter. Atoms, he believed were tiny magnets of different sexes.

Petty’s most notable application of physical principles to a practical problem was in the development of his famous twin-hulled ships. He designed and constructed three of them between 1662 and 1664 and another in 1684. The first two ships were rather successful, but the third sank in a storm with all hands abaord, and the fourth was a complete failure. His concept was nevertheless valid and is exemplified in the modern catamaran.

Petty’s writings that are relevant to the social sciences were his most enduring achievement. The time spent managing his Irish holdings undoubtedly reduced the time he could devote to scholarly writings. On the other hand, those holdings provided the incentive and orientation for his writings on political arithmetic.

Inseparable from Petty’s writings is John Graunt’s important Natural and Political Observations Mentioned in a Following Index, and Made Upon the Bills of Mortality; published in January 1662, it started the sciences of demography and statistics. In spite of Graunt’s name on the title page and his election to the Royal Society on the book’s merits, seven contempraries referred to Petty as the author. The available evidence does not establish their claim. Petty and Graunt became friends around 1650 and remained so until Graunt’s death. It seems likely that Petty discussed with Graunt the analysis of the London bills of mortality, and perhaps the book would not have been published without Petty’s assistance and encouragement.

Petty’s writings most comparable to Graunt’s Observations are ten brief essays (1682–1687) on the population of London, Dublin, Paris, Rome, and other cities. These essays reveal Petty’s n appreciation of the importance of population as an economic factor. Because there were few vital statistics for any city except London, he relied upon unreliable indexes of population, such as the number of chimneys.

Although his figures were sometimes questionable, Petty was the first economic theorist to make a significant attempt to base economic policy upon statistical data. His Treatise of Taxes and Contributions (1662), possibly his best work, discussed the economy of Ireland and England and attempted to formulate sound policies for promoting wealth and collecting taxes. He was the first to emphasize the value of labor as a part of national wealth, and he also provided an important analysis of rents. His short Verbum sapienti, written about 1665 and published in 1691, is more quantitative and contains the first estimate of national incomes and the first discussion of the velocity of money. The Political Anatomy of Ireland, written about 1672 and published in 1691, also on economic policy, is supported by economic geography. In Political Arithmerick, written 1671-1676 and published in 1690, Petty extended his discussion to a comparison of the wealth and economic policies of England and France. He argued the benefits of a division of labor and the gains from foreign trade in Another Essay in Political Arithmetick Concerning the Growth of the City of London (1683). He also left other manuscripts on the Irish and English economy that have been published only recently. These include A Treatise of Ireland (1899), written in 1687 as advice for James II—advice neither requested nor heeded.

Petty’s writings were, nevertheless, influential in England, and as an economic theorist he was not surpassed before 1750.


I. Original Works. Excellent detailed bibliographies of Petty’s published writings and some of his MSS are Charles Henry Hull, ed., The Economic Writings of Sir William Petty Together With the Observations Upon the Bills of Mortality, More Probably by Captain John Graunt, II (Cambridge, 1899; facs,ed.,New York, 1963),633–657; Yann Morvran Goblet [pseudonym for Louis Treguiz], La transformation de la geographie politique de l’Ireland au XVII Siecle dans lels cartes et essais anthropogeographiques de Sir William Petty, I (Paris, 1930),ix-xxiii; and Geoffrey Keynes, A Bibliography of Sir William Petty F.R.S. and Observations on the Bills of Mortality by John Graunt F.R.S.(Oxford, 1971).

Twelve of Petty’s treatises have been reprinted with introductions and notes by Henry Hull, in the work mentioned above. Other works by Petty include The History of the Survey of Ireland, Commonly Called the Down Survey A.D. 1655–6, Thomas Aiskew Larcom, ed. (Dublin, 1851; facs. ed. New York, 1967); and A Census of Ireland circa 1659, SÉamus Pender ed. (Dublin, 1939). Lord Landowne has edited three important collections of Petty’s MSS: The Petty Papers: Some Unpublished Writings of Sir William Petty, 2 vols. (London-Boston, 1927; facs. ed. New York, 1966); The Petty-Southwell Correspondence, 1676–1687 (London, 1928; facs. ed., New York, 1967) and The Double Bottom or Twin-Hulled Ship (Oxford, 1931).

II. Secondary Literature. The most important contemporary accounts of Petty are by John Aubrey and John Evelyn; both are reprinted in Keynes’ Bibliography, 85–95. The most detailed, and still essential biography is Edmund George Petty Fitzmaurice also wrote the account in the The Dictioinary of National Biography, new ed., XV, 999–1005. A very interesting recent biography is Eric Strauss, Sir William Petty, Portrait of a Genius (London-Glencoe,I11., 1954), which includes a discussioin of Petty’s work.

Bacon and Hartlib’s influence on Petty is admirably discussed in Walter E. Houghton,“The History of Trades: Its Relation to Seventeenth-Centuury thought as Seen in Bacon, Petty, Evelyn, and Boyle,” Journal of the History of Ideas 2(1941), 33–60, repr. in Philip P.Wiener and Aaron Naland, eds., Roots of Scientific Thought, a Cultural Perspective (New York, 1957), 354–381.

On Petty’s participation in the beginnings of the Royal Society, see Thomas Sprat, The History of the Royal Society of London for the Improving of Natural Knowledge (London, 1667), facs. ed., Jackson I. Cope and Harold Whitmore Jones, eds. (St.Louis-London, 1958); Thomas Birch, A History of the Royal Society for Improving of Natural Knowledge, From Its First Rise, I (London, 1756); Irvine Masson and A. J. Youngson, “Sir William Petty, F. R. S. (1623-1687), “ in The Royal Society, Its Origins and Founders, Harold Hartley, ed., (London, 1960), 79–90; and Margery Purver, The Royal Society: Concept and Creation (Cambridge, Mass.,1967).

On Petty’s Discourse Made Before the Royal Society the 26. of November 1674. Concerning the Use of Duplicate Proportion in Sundry Important Particulars: Together With a New Hypothesis of Springing or Elastique Motions, see A. Wolf, F. Dannemann, A. Armitage, and Douglas McKie, A History of Science, Technology and Philosophy in the 16th & 17th Centuries 2nd ed. (New York, 1950), 484; and Robert H. Kargon, “William Petty’s Mechanical Philosophy,” in Isis56 (1965), 63–66. On Petty’s ships, see Lord Lansdowne’s intro. to The Double Bottom or Twin-Hulled Ship of Sir William Petty (Oxford, 1931). On the relationship between science and technology in Petty’s work, Hessen’s famous arguments concerning Newton would for the most part apply; see Boris M. Hessen, “The Social and Economic Roots of Newton’s ’Principia,’” in Science at the Cross Roads: Papers Presented to the International Congress of the History of Science and Technology in London From June 20th to July 3rd, 1931 by the Delegates of the U.S.S.R. (London, 1931), 151–176; repr. as separate book (New York, 1971).

On the Down Survey, see Petty’s account mentioned above. On the census, see Pender’s intro to the volume cited above. The Down Survey, the maps, Petty’s contributions to geography, and his career in Ireland are thoroughly and admirably discussed by Goblet (Treguiz), La transformation de la geographie politique See also his A Topographical Index of the Parishes and Townlands of Ireland in Sir William Petty’s MSS. Barony Maps (c.1655–9) (Bibliotheque Natioinal de Paris, fonds anglais, nos.1&2) and Hiberniae Delineatio (c. 1672) (Dublin, 1932); and SeanO’Domhnaill“ The Mapsp of the Down Survey,” in Irish Historical Studies 3(1943), 381-392.

The authorship of Graunt’s Natural and Political Observations has been discussed in C. H. Hull, ed., Economic Writings of Sir William Petty “Sir William Petty, I (Cambridge, 1899), xxxix-Iiv; Wilson Lloyd Bevan, “Sir William Petty. A Study in English Economic Literature,” in publications of the American Economic Association, 9, no. 4 (1894), 42-46; Lansdowne, The Petty Papers II,273-284, and The Petty-Southwell Correspondence, xxiii-xxxii; Major Greenwood, Medical Statistics From Gruant to Farr (Cambridge, 1948), 36-39; D. V. Glass, “John Graunt and His His Natural and Political Observations in Notes and Records. Royal Society of London, 19 (1964), 78-89, 97-100; P. D. Groenewegen,“ Authorship of the Natural and Political Observations Upon the Bills of Mortality,” in Journal of the History of Ideas28(1967), 601-602; and Geoffrey Keynes, A Bibliography of Sir William Petty (Oxford, 1971), 75-77.

On Petty’s contributions to demography and statistics, see Harald Westergaard,Contributions to the History of Statistics (London, 1932; facs. ed. New York, 1968), 28-31; Greenwood, Medical Statistics 2-27; Wolf et al., A History of Science II, bk. 7; James Bonar, Theories of Population From Raleigh to Arthur Young (London, 1931; facs. ed., London, 1966), ch.3; and Charles F. Mullett, “Sir William Petty on the Plague,” in Isis28 (1938), 18-25. Petty’s interest in the application of his demographic ideas in the United States is discussed in James J.Cassedy, Demography in Early America: Beginings of the Statistical Mind (Cambridge, Mass., 1969).

On Petty’s contributions to economics, see Bevan, Sir William Petty; Phyllis Deane, “William Petty,” in International Encyclopedia of the Social Sciences XII (1968),66-68; William Letwin, The Origins of Scientific Economics (London, 1963; Garden City, N.Y., 1964), ch. 5; Walter Muller, Sir William Petty als politischer Arithmetiker: Eine soziologisch-statistische Studie (Gelnhausen, 1932); Maurice Pasquier, Sir William Petty, sesideas economiques (Paris, 1903); and Eric Roll, A History of Economic Thought 2nd ed. (New York, 1942), 99-114.

Frank N. Egerton III

Petty, William

views updated May 17 2018

Petty, William



William Petty (1623–1687), the English economist and first systematic exponent of “the art of political arithmetic,” was a self-made man with a wide range of talents and immense mental energy. He was the son of a clothier, traditionally described by his biographers as “poor,” but if, as is likely, Petty’s father left him the good house and 8 acres of land that he owned in his birthplace, Romsey, in 1685, the family was comfortably above the poverty line. Certainly, when the young Petty went to sea as a cabin boy at the age of about 14, he was sufficiently literate in Latin and Greek to gain entry to the Jesuits’ college at Caen, where he was put ashore on breaking a leg; there he studied Latin, Greek, French, and mathematics. Then, after a short spell in the Royal Navy, he went on to study medicine at the universities of Utrecht, Amsterdam, Paris, and Oxford. By 1651 he had taken his Oxford degree of Doctor of Physic and entered the London College of Physicians. At the age of 28, he became vice-principal of Brasenose College and professor of anatomy at Oxford.

Although one of the leading intellectuals of his day and a founding member of the Royal Society, Petty was a man of the world rather than a scholar. He wrote more than he read. He was a persistent inventor: he patented a double-writing device before he got his medical degree, and he pursued his design for a twin-hulled ship through four prototypes. He worked out a scheme for the rebuilding of London after the Great Fire of 1666. In 1652 he went to Ireland as physician-general to the army, which was no sinecure in a country ravaged by the plague and other lethal epidemic diseases. Within two years of his arrival in Ireland he had taken over the complex task of surveying the forfeited estates of the Irish rebels as a basis for their redistribution among the English conquerors. This task, too, he performed with his usual efficiency and drive and with the determination and pugnacity which earned him many enemies and carried him into countless lawsuits. He spent much of his working life defending his Irish survey and handling his own Irish estates, but he still managed to read a number of communications to the Royal Society on topics varying from dyeing practices in the clothing trade to the testing of mineral waters and to achieve a formidable and serious literary output on economic, demographic, naval, medical, and scientific subjects.

A good deal has been written about Petty, and the published opinions of his contemporaries leave no doubt of the respect and esteem with which he was regarded. It is unlikely that he was author, as has been claimed, of the “Natural and Political Observations Upon the Bills of Mortality,” which was signed by his friend John Graunt (see Graunt [1662] 1963, vol. 2, pp. 314–435), but he could well have been; and the title page of his own “Observations Upon the Dublin-Bills of Mortality” ([1683] 1963, vol. 2, pp. 479–491) explicitly associates him with the earlier work, which was a pathbreaker in demographic analysis. John Aubrey, his first biographer, the diarists John Evelyn and Samuel Pepys, and the economist and statesman, Davenant, all men of distinction in their own right, regarded Petty as one of the outstanding men of their time.

Petty’s claim to fame as an economist lies not so much in his originality or his theoretical ability as in his analytical skill. His insistence on measurement and his clear schematic view of the economy make him the first econometrician, and he was constantly evolving and using concepts and analytical methods that were in advance of his time. His evaluation of the gain from foreign trade in “Another Essay in Political Arithmetick Concerning the Growth of the City of London” ([1682] 1963, vol. 2, pp. 451–478) is based on a statement of the benefits of the division of labor and specialization and was written a century before Adam Smith’s famous account. Petty put so much stress on the role of labor in creating wealth that he has been regarded (for instance, by Marx) as an early exponent of the labor theory of value. But, as is shown by a characteristic and frequently quoted passage from his “Treatise of Taxes and Contributions” ([1662] 1963, vol. 1, pp. 1–97)— “Labour is the Father and active principle of Wealth as Lands are the Mother”—his theory of production and value is based on the two original factors of production of the early economists. He was the author of the first known national income estimates, in “Verbum sapienti” ([1665] 1963, vol. 1, pp. 99120), “Political Arithmetick” ([c. 1676] 1963, vol. 1, pp. 233–313), and “Treatise of Ireland” ([1687] 1963, vol. 2, pp. 545–621), although he did not trouble to define or develop his concepts and was rough, even careless at times, in his use of figures. Some of the calculations in his “Treatise of Taxes and Contributions” and elsewhere are essentially exercises in what is now called “cost-benefit analysis.” He was the first writer, so far as we know, to grasp the concept of the velocity of money, again in “Verbum sapienti,” although in his “Quantulumcunque Concerning Money” ([1695] 1963, vol. 2, pp. 437–448) there is no trace of it. He was not above manipulating his data in ways that would justify his polemical arguments, and it would be rash to accept his statistics uncritically. But he was no slave to political prejudice, and his analysis of the economy of his time for England and Ireland —for example, “The Political Anatomy of Ireland” ([1671–1676] 1963, vol. 1, pp. 121–231)— and his various essays on “political arithmetick” are both shrewd and penetrating.

Phyllis Deane

[Other relevant material may be found in the biography ofGraunt.]


(1662) 1963 Treatise of Taxes and Contributions. Volume 1, pages 1–97 in William Petty, The Economic Writings … New York: Kelley.

(1662–1695) 1963 The Economic Writings of Sir William Petty. 2 vols. Edited by Charles H. Hull. New York: Kelley. → Contains Petty’s main writings and a general bibliography.

(1665) 1963 Verbum sapienti. Volume 1, pages 99–120 in William Petty, The Economic Writings … New York: Kelley. → Written in 1665; first published posthumously in 1691.

(1671–1676) 1963 The Political Anatomy of Ireland. Volume 1, pages 121–231 in William Petty, The Economic Writings … New York: Kelley. → Written between 1671 and 1676; first published posthumously in 1691.

(c. 1676) 1963 Political Arithmetick. Volume 1, pages 233–313 in William Petty, The Economic Writings … New York: Kelley. → First written c. 1676; first published surreptitiously in 1683 as “England’s Guide to Industry.” The first authorized edition was published posthumously in 1690 by Petty’s son.

(1682) 1963 Another Essay in Political Arithmetick Concerning the Growth of the City of London, 1682. Volume 2, pages 451–478 in William Petty, The Economic Writings… New York: Kelley.

(1683) 1963 Observations Upon the Dublin-Bills of Mortality, 1681, and the State of That City. Volume 2, pages 479–491 in William Petty, The Economic Writings . … New York: Kelley.

(1687) 1963 Treatise of Ireland, 1687. Volume 2, pages 545–621 in William Petty, The Economic Writings … New York: Kelley. → Written in 1687; first published posthumously in 1899.

(1695) 1963 Sir William Petty’s Quantulumcunque Concerning Money, 1682. Volume 2, pages 437–448 in William Petty, The Economic Writings … New York: Kelley. → Published posthumously.

The Double Bottom or Twin-hulled Ship of Sir William Petty. Edited by the Marquis of Lansdowne. Oxford: Roxburghe Club, 1931.

History of the Cromwellian Survey of Ireland: A.D. 1655–1656. Edited by Thomas A. Larcom. Irish Archaelogical and Celtic Society Publications, Vol. 15. Dublin Univ. Press, 1851. → Commonly called the “Down Survey.”

The Petty Papers. 2 vols. Edited by the Marquis of Lansdowne. London: Constable, 1927.

The Petty-Southwell Correspondence: 1676–1687. Edited by the Marquis of Lansdowne. London: Constable, 1928.


Aubrey, John (1898) 1957 Sir William Petty. Pages 237–241 in John Aubrey, Brief Lives. Edited from the original manuscripts and with a life of John Aubrey by Oliver L. Pick. Ann Arbor: Univ. of Michigan Press.

Bevan, Wilson L. 1894 Sir William Petty: A Study in English Economic Literature. Volume 9, pages 370472 in American Economic Association, Publications. Baltimore: The Association.

Fitzmaurice, Edmond G. P. 1895 The Life of Sir William Petty: 1623–1687. London: Murray. → Contains Petty’s autobiographical will.

Graunt, John (1662) 1963 Natural and Political Observations Upon the Bills of Mortality. Volume 2, pages 314–435 in William Petty, The Economic Writings … New York: Kelley. → The uthorship of this work is in doubt.

Greenwood, Major 1928 Graunt and Petty. Journal of the Royal Statistical Society 91:79–85.

Pasquier, Maurice 1903 Sir William Petty: Ses idées économiques. Paris: Giard & Brière.

Strauss, Emil 1954 Sir William Petty: Portrait of a Genius. London: Bodley Head; Glencoe, III.: Free Press.

Petty, William (1623–1687)

views updated May 29 2018

PETTY, WILLIAM (16231687)

PETTY, WILLIAM (16231687), English political economist. Born in Romsey, Hampshire, William Petty was the son of a tailor. At age thirteen, Petty became a cabin boy on a merchant ship. He broke his leg at sea and left the ship in Caen, France, where he enrolled in a Jesuit school and mastered Latin, Greek, and French. On returning to England, he joined the Navy, but in 1643, with the outbreak of the Civil War, he went to the Netherlands to study medicine at Utrecht, Leiden, and Amsterdam, and then to Paris, where he became acquainted with Thomas Hobbes and Marin Mersenne. In 1646, Petty returned to England and later studied medicine at Oxford, receiving his M.D. in 1649. He was appointed professor of anatomy at Brasenose College, Oxford, and then professor of music at Gresham College, London. In 1652, Petty became the physician-general to Oliver Cromwell's army in Ireland. Petty directed the famous Down Survey, using the army to map all Irish lands in just one year. In the process, he acquired an immense amount of property, especially in County Kerry. In 1661, Petty was knighted by Charles II. In 1667, he married Elizabeth Fenton and they had two sons and one daughter who survived to adulthood.

Petty was a virtuoso. In 1662, he became a charter member of the Royal Society in London. (He was also one of the founders and the first president of the Dublin Philosophical Society.) He is most famous for his contributions to economics and his promotion of a new science he called political arithmetic. The aim of political arithmetic was to treat political problems (broadly defined) mathematically. One of the most pressing problems for Petty was population. Petty viewed labor as essential to the production of wealth and advocated means to increase population and to measure it. To this end, he urged the English and Irish governments to collect regular statistics on births, deaths, and total population. In his Treatise of Taxes (1662), he argued that the use of political arithmetic could rationalize tax collection and thus put the nation on more stable financial ground.

Petty was a close friend of John Graunt, who had pioneered the numerical study of society. Like Graunt, Petty investigated bills of mortality for a variety of purposes, ranging from determining the optimum number of physicians for England to demonstrating the superiority of England to France. In a series of pamphlets, Petty developed methods to estimate population from the number of houses and from the number of burials and christenings. He stated that the number of deaths due to contagious, acute, and chronic diseases would provide a measure of the salubrity, or healthfulness, of a specific parish. He compared the mortality rates at London hospitals with those of Paris hospitals and concluded that London's were lower.

Petty was a prolific writer and published numerous books, pamphlets, and articles. Many other writings were published posthumously. He has been regarded by later writers, including Karl Marx, as the founder of English political economy. More recently, historians have emphasized his contributions to the quantifying spirit of the eighteenth century and his advocacy of creating new methods of governance (especially statistics) that are characteristic of modern societies.

See also Census ; Cromwell, Oliver ; Graunt, John ; Hobbes, Thomas ; Public Health ; Statistics ; Taxation .


Hull, Charles Henry, ed. The Economic Writings of Sir William Petty: Together with the Observations upon the Bills of Mortality More Probably by John Graunt. Reprint ed. Fairfield, N.J., 1986. First ed. Cambridge, U.K., 1899.

Mykkänen, Juri. "'To Methodize and Regulate Them': William Petty's Governmental Science of Statistics." History of the Human Sciences 7 (1994): 6588.

Poovey, Mary. A History of the Modern Fact: Problems of Knowledge in the Sciences of Wealth and Society. Chicago, 1998.

Roncaglia, Alessandro. Petty: The Origins of Political Economy. Translated by Isabella Cherubini. Armonk, N.Y., 1985.

Rusnock, Andrea Alice. Vital Accounts: Quantifying Health and Population in Eighteenth-Century England and France. Cambridge, U.K., 2002.

Strauss, E. Sir William Petty: Portrait of a Genius. London, 1954.

Andrea Rusnock

Petty, William

views updated May 21 2018



Sir William Petty was born in London in very modest circumstances, the son of a clothmaker. After some years in the navy of King Charles I, he studied medicine in the Netherlands; in Paris, where he became a friend of the philosopher Thomas Hobbes; and at Oxford. In 1650, at the age of twenty-seven, he became professor of anatomy at Oxford, resigning the next year when he was appointed physician-general to Cromwell's army in Ireland.

Much of the rest of Petty's life was spent in Ireland in various capacities. He organized a major topographical survey that was needed for the redistribution of the forfeited property of Catholic landowners; after the restoration of Charles II he was a member of parliament for Ireland and was engaged in managing an industrial colony on the estate he had acquired in County Kerry. In his London life he was one of the group of philosophers and scientists, including Robert Boyle and John Graunt (1620–1674), who founded the Royal Society. He was knighted in 1661.

Petty's major intellectual contributions to both economics and demography fall under the broad rubric of political arithmetic, a term he invented. This was the application of Francis Bacon's (1561–1626) methods of natural philosophy to understanding social conditions and economic life–on the assumption that the body politik could be studied quantitatively in the same manner as the body natural. In his account of Petty in Brief Lives (c. 1690), John Aubrey concisely, if somewhat dismissively, characterized the approach as "reducing polity to numbers." Petty's work laid the foundations for the development of systematic social and economic statistics by subsequent scholars such as Charles Davenant (1656–1714) and Gregory King (1648–1712). On the basis of his pamphlet Verbum Sapienti (1690, a posthumous publication, like most of Petty's writings) Richard Stone (1997) calls Petty "the originator of national accounting." This general perspective and its influence on the thinking of his contemporaries and successors is the main reason Petty has a place in the history of demography: Population dynamics were to him an integral part of social accounting.

Petty also made specific demographic contributions, in particular in estimating mortality and population size, chiefly of major cities. He played a role, most likely minor, in the preparation of Graunt's pathbreaking Observations on the (London) bills of mortality (1662). Petty has sometimes been credited with virtual authorship of this work, but a detailed investigation by his later editor Charles Henry Hull found little evidence to support that contention. Stone agrees that such an attribution is baseless. Petty admired Graunt's work and drew on it in his own studies, especially of the Dublin bills of mortality.

His estimates of city sizes–based on calculations such as the number of burials divided by the supposed death rate or the number of houses multiplied by the average household size (guessed)–he recognized as highly conjectural, needing to be replaced by independent enumerations. (His population of London was much too large, that of Paris too small.) At the end of his Observations on the Dublin Bills (1683), he wrote: "Without the knowledge of the true number of the people, as a principle, the whole scope and use of keeping bills of birth and burials is impaired; wherefore by laborious conjectures and calculations to deduce the number of people from the births and burials, may be ingenious, but very preposterous." Petty's land survey of Ireland, the results of which were published in his Political Anatomy of Ireland (1691), was effectively Ireland's first census (1659).

See also: Demography, History of; Graunt, John; King, Gregory; Population Thought, History of.


selected works by william petty.

Petty, William. 1686. An Essay Concerning the Multiplication of Mankind: Together with Another Essay in Political Arithmetick, Concerning the Growth of the City of London: with the Measures, Periods, Causes, and Consequences thereof, 1862. 2nd edition. London: Mark Pardoe. Excerpted in Population and Development Review 10(1984): 127–133.

——. 1690. Political Arithmetick, or, A discourse concerning the extent and value of lands, people, buildings, husbandry, manufacture, commerce,…, as the same relates to every country in general… London: Robert Clavel and Hen. Mortlock.

——. 1691. The Political Anatomy of Ireland… To which is added Verbum sapienti, or, An account of the wealth and expences of England, and the method of raising taxes in the most equal manner… London: D. Brown and W. Rogers. Facsimile edition: Shannon, Ireland: Irish University Press, 1970.

——. [1899] 1964. The Economic Writings of Sir William Petty, ed. Charles H. Hull. 2 vols. New York: A. M. Kelly.

selected works about william petty.

Aubrey, John. 1898. Brief Lives … Set Down between the Years 1669 & 1696. Oxford: Clarendon Press.

Hull, Charles H. 1900. "Petty's Place in the History of Economic Theory." Quarterly Journal of Economics 14(4): 307–340.

Stone, Richard. 1997. Some British Empiricists in the Social Sciences 1650–1900. Cambridge, Eng.: Cambridge University Press.

Geoffrey McNicoll

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