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{{Short description|English economist and philosopher (1623–1687)}}
{{other people}}
{{EngvarB|date=August 2014}}
{{Use dmy dates|date=August 2020}}
{{more citations needed|date=May 2014}}
{{Infobox philosopher 
| region          = [[Western philosophy]]
| era             = [[17th-century philosophy]]<br />([[Modern philosophy]]) 
| image     = Sir William Petty.jpg
| caption   = Sir William Petty, [[mezzotint]] by [[John Smith (engraver, born 1652)|John Smith]] after [[John Closterman]]
| honorific_prefix    = Sir
| name             = William Petty
| honorific_suffix    = {{post-nominals|country=GBR|size=100%|FRS}}
| birth_date       = {{birth date|df=y|1623|5|26}}
| birth_place      = [[Romsey]], [[Hampshire]], [[Kingdom of England|England]]
| death_date       = {{death date and age|df=y|1687|12|16|1623|5|26}}
| death_place       = [[London]], England
| school_tradition = [[Classical economics]]
| main_interests   = [[Political philosophy]], ethics, economics, medicine
| notable_ideas    = [[Division of labour]], [[fiscal policy|fiscal theory]], [[monetary theory]], [[national income|national income accounting]], [[economic statistics]],  [[gross domestic product]]
}}

'''Sir William Petty''' {{post-nominals|country=GBR|size=100%|FRS}} (26 May 1623 – 16 December 1687) was an English economist, physician, scientist and philosopher. He first became prominent serving [[Oliver Cromwell]] and the [[Commonwealth of England|Commonwealth]] in [[Cromwellian conquest of Ireland|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 [[Charles II of England|King Charles II]] and [[James II of England|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<ref>{{Cite journal |last=Bevan |first=Wilson Lloyd |date=1894 |title=Sir William Petty: A Study in English Economic Literature |url=https://www.jstor.org/stable/2485672 |journal=Publications of the American Economic Association |volume=9 |issue=4 |pages=13–102 |jstor=2485672 |issn=1049-7498}}</ref><ref>{{Cite journal |last=Hull |first=Charles H. |date=1900 |title=Petty's Place in the History of Economic Theory |url=https://www.jstor.org/stable/1882563 |journal=The Quarterly Journal of Economics |volume=14 |issue=3 |pages=307–340 |doi=10.2307/1882563 |jstor=1882563 |issn=0033-5533|url-access=subscription }}</ref><ref>{{Cite journal |last=Fox |first=Adam |date=2009 |title=Sir William Petty, Ireland, and the Making of a Political Economist, 1653-87 |url=https://www.jstor.org/stable/20542917 |journal=The Economic History Review |volume=62 |issue=2 |pages=388–404 |doi=10.1111/j.1468-0289.2008.00455.x |jstor=20542917 |issn=0013-0117|url-access=subscription }}</ref> and his methods of ''political arithmetic''. He was knighted in 1661.

==Life==

=== Early life ===
Petty was born in [[London]], where his father and grandfather were [[Cloth merchant|clothier]]s.  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 "[[flagellation|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 [[Jesuit]]s in [[Caen]], supporting himself by teaching English. After a year, he returned to England, and had by now a thorough knowledge of Latin, [[Ancient Greek|Greek]], French, mathematics, and astronomy.<ref name="Percy on Petty (1932)">{{cite book |last1=Percy Kirkpatrick |first1=T. Percy C. (Thomas Percy Claude) |title=Sir William Petty (1623-1687) |date=1932 |publisher=[Ireland] : [The Irish Journal of Medical Science] |url=https://archive.org/details/b30629202/page/n1/mode/2up |author1-link=Percy Kirkpatrick }}</ref>

=== Career ===
===At Oxford===
After the [[Siege of Oxford#Third siege (1646)|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 of Oxford|University]]. He befriended [[Samuel Hartlib|Hartlib]] and [[Robert Boyle|Boyle]] and became a member of the [[Oxford Philosophical Club]].

==== Musician, doctor, academic and surveyor ====
By 1651, Petty was an anatomy instructor at [[Brasenose College, Oxford]], as deputy to [[Thomas Clayton the younger]].<ref name="DNB">{{cite DNB|wstitle=Petty, William (1623-1687)}}</ref><ref>{{cite book|author=Nicholas Tyacke|title=The History of the University of Oxford: Volume IV: Seventeenth-Century Oxford|url=https://books.google.com/books?id=J06RQ3tXuuQC&pg=PA543|access-date=5 November 2012|date=4 December 1997|publisher=Oxford University Press|isbn=978-0-19-951014-6|page=543}}</ref> With a second doctor, [[Thomas Willis]], Petty was involved in treating [[Anne Greene]], a woman who survived her own hanging and was subsequently pardoned because her survival was widely held to be an act of [[miracle|divine intervention]]. The event was widely written about at the time, and helped to build Petty's career and reputation.<ref name="miracles">{{Cite book | title=Miracles in Enlightenment England | last=Shaw | first=Jane | publisher=Yale University Press | location=New Haven, Connecticut | year= 2006| isbn=0300197683| url=https://books.google.com/books?id=4_UXe_Cat7wC&pg=PA58}}</ref> He was also appointed [[Gresham Professor of Music]] by the [[Corporation of the City of London]] in 1650, retaining the post until 1660.<ref>[https://web.archive.org/web/20041019231900/http://www.gresham.ac.uk/special/professors.htm list of professors] of Gresham College (via [[archive.org]]).</ref>
[[File:SirWilliamPetty.jpg|thumb|left|200px|William Petty, c. 1650]]
In 1652, he took a leave of absence and travelled with [[Oliver Cromwell]]'s [[Cromwellian conquest of Ireland|army in Ireland]] as physician-general, responsible to Cromwell's son-in-law, [[Charles Fleetwood]]. His opposition to conventional universities, being committed to 'new science' as inspired by [[Francis Bacon]] and imparted by his afore-mentioned acquaintances, perhaps pushed him from Oxford. He was pulled to Ireland perhaps by a sense of ambition and desire for wealth and power. He secured the contract for charting Ireland in 1654, so that those who had lent funds to Cromwell's army might be repaid in land – a means of ensuring the army was self-financing. This enormous task, which he completed in 1656, became known as the [[Down Survey]], later published (1685) as ''[[Hiberniae Delineatio]]''.<ref>{{cite book |last=De Breffny |first=Brian |author-link= |date=1983 |title=Ireland: A Cultural Encyclopedia |url= |location=London |publisher=Thames and Hudson |page=50 |isbn=}}</ref> As his reward, he acquired approximately {{convert|30000|acre|km2}} in [[Kenmare]], in southwest Ireland, and £9,000. This personal gain to Petty led to persistent court cases on charges of bribery and [[English trusts law|breach of trust]], until his death.

Back in England, as a Cromwellian supporter, he ran successfully for Parliament in 1659 for [[West Looe (UK Parliament constituency)|West Looe]].<ref>{{ODNBweb|id=22069|title=Petty, William|first=Toby|last=Barnard}}</ref>

==== Projector ====
[[File:WIlliam Petty's Baronetcies in Kerry.png|thumb|right|Petty's baronetcies in Kerry]]
Petty gained possession of the three baronies of [[Iveragh]], [[Glanarought]] and [[Dunkerron Castle|Dunkerron]] in [[County Kerry]].<ref name="Barnard">{{cite journal |last1=Barnard |first1=T. C. |date=1982 |title=Sir William Petty as Kerry Ironmaster |journal=Proceedings of the Royal Irish Academy. Section C: Archaeology, Celtic Studies, History, Linguistics, Literature |volume=82C |pages=1–32 |issn=0035-8991 |jstor=25506081}}</ref> He soon became a [[Projector (business)|projector]], developing extensive plans for an [[ironworks]] and a [[fishery]] on his substantial estates in Kerry. Although he had great expectations of his application of his scientific methods to improvement, little came of these.<ref name="Jackson">{{cite book |last1=Jackson |first1=Alvin |url=https://books.google.com/books?id=qIYfAwAAQBAJ&pg=PT484 |title=The Oxford Handbook of Modern Irish History |date=2014 |publisher=OUP Oxford |isbn=978-0-19-166760-2 |location=Oxford |language=en}}</ref> He began by applying his political arithmetic to his own estates, surveying the population and livestock to develop an understanding of the land's potential.<ref name="Barnard" /> The ironworks was established in 1660.<ref name="Wheatley">{{cite journal |last1=Wheatley |first1=Henry B. |date=1913 |title=Charcoal Ironworks |journal=Journal of the Royal Society of Arts |volume=61 |issue=3175 |pages=977–983 |issn=0035-9114 |jstor=41341249}}</ref>

==== Natural philosopher ====
Despite his political allegiances, Petty was well-treated at the [[English Restoration|Restoration]] in 1660, although he lost some of his Irish lands. [[Charles II of England|Charles II]], at their first meeting, brushed aside Petty's apologies for his past support for Cromwell, "seeming to regard them as needless", and discussed his experiments into the mechanics of shipping instead.<ref>Fraser, Antonia, ''King Charles II'' Mandarin edition 1993 p.189</ref>

In 1661 he was elected as a Member of Parliament for [[Inistioge (Parliament of Ireland constituency)|Inistioge]] in the [[Parliament of Ireland]]. In 1662, he was admitted as a charter member of the [[Royal Society]] of the same year. This year also saw him write his first work on economics, ''Treatise of Taxes and Contributions''. Petty counted naval architecture among his many scientific interests. He had become convinced of the superiority of double-hulled boats, although they were not always successful; a ship called the ''Experiment'' reached [[Porto]] in 1664, but sank on the way back.

=== Ireland and later life ===
Petty was knighted in 1661 by Charles II and served as MP for [[Inistioge (Parliament of Ireland constituency)|Inistioge]] from 1661-66. He remained in Ireland until 1685. He was a friend of [[Samuel Pepys]].

The events that took him from Oxford to Ireland marked a shift from medicine and the physical sciences to the social sciences, and Petty lost all his Oxford offices. The social sciences became the area that he studied for the rest of his life. His focus became greater income from Irish colonization, and his works describe that country and propose many remedies for what he characterized as its backward condition. He helped found the [[Royal Dublin Society|Dublin Society]] in 1682. Returning ultimately to London in 1685, he died in 1687. He was buried in [[Romsey Abbey]].

==Family==
William Petty married [[Elizabeth Waller, Baroness Shelburne|Elizabeth Waller]] in 1667. She was a daughter of the [[regicide]] Sir [[Hardress Waller]] (whose life was spared after the Restoration) and [[Elizabeth Dowdall]]. She had been previously married to [[Sir Maurice Fenton, 1st Baronet|Sir Maurice Fenton]], who died in 1664. She was given the title Baroness Shelburne for life.{{sfn|Burke|Burke|1844|p=605}} They had three surviving children:
* [[Charles Petty, 1st Baron Shelburne]]
* [[Henry Petty, 1st Earl of Shelburne]]
* Anne, who married [[Thomas Fitzmaurice, 1st Earl of Kerry]].

Neither Charles nor Henry had male issue and the Shelburne title passed by a special remainder to Anne's son [[John Petty, 1st Earl of Shelburne]], who took his mother's surname, and whose descendants hold the title [[Marquis of Lansdowne]]. Her grandson [[William Petty, 2nd Earl of Shelburne]], praised her as a woman of strong character and intelligence, the only person who could manage her bad-tempered and tyrannical husband.

==Economic works and theories==
[[File:Petty - Economic writings, 1899 - 5179309.tif|thumb|[[The Economic Writings of Sir William Petty|''The Economic Writings'', 1899]]]]
Two men crucially influenced Petty's economic theories. The first was [[Thomas Hobbes]], for whom Petty acted as personal secretary. According to Hobbes, theory should set out the rational requirements for "civil peace and material plenty". As Hobbes had centred on peace, Petty chose prosperity.{{Citation needed|reason=This attributes very specific motives to Petty; is there any documentary evidence supporting such an attribution?|date=September 2015}}

The influence of [[Francis Bacon]] was also profound. Bacon, and indeed Hobbes, held the conviction that mathematics and the senses must be the basis of all rational sciences. This passion for accuracy led Petty to famously declare that his form of science would only use measurable phenomena and would seek quantitative precision, rather than rely on comparatives or superlatives, yielding a new subject that he named "political arithmetic". Petty thus carved a niche for himself as the first dedicated economic scientist, amidst the merchant-pamphleteers, such as [[Thomas Mun]] or [[Josiah Child]], and philosopher-scientists occasionally discussing economics, such as [[John Locke]].

He was indeed writing before the true development of [[political economy]]. As such, many of his claims for precision are of imperfect quality. Nonetheless, Petty wrote three main works on economics, ''Treatise of Taxes and Contributions'' (written in 1662), ''Verbum Sapienti'' (1665) and ''Quantulumcunque Concerning Money'' (1682). These works, which received great attention in the 1690s, show his theories on major areas of what would later become economics. What follows is an analysis of his most important theories, those on fiscal contributions, national wealth, the money supply and circulation velocity, value, the interest rate, international trade and government investment.

Many of his economic writings were collected by [[Charles Henry Hull]] in 1899 in ''[[The Economic Writings of Sir William Petty]]''.

Hull, in his scholarly article '[[Petty's Place in the History of Economic Theory]]' (1900) proposed a division of the economic writings of Petty in three (or four) groups:
* the first group, written when Petty had returned to London after finishing his "[[Down Survey]]" in Ireland, consists mainly of ''A Treatise of Taxes & Contributions'' (written and first published 1662) and ''Verbum Sapienti'' (written 1665, printed 1691). These texts relate to the discussions about fiscal issues, following the [[Restoration (1660)|Restoration]] and the expenses of the [[first Dutch war]].
* the second group holds ''The Political Anatomy of Ireland'' and ''Political Arithmetick.'' These texts were written some ten years later in Ireland. As Hull writes, the "direct impulse to their writing came from Dr. [[Edward Chamberlayne]]'s ''Present State of England'', published 1669".
* Again ten years later the third group of pamphlets was written, that were contributions to the dispute whether London was a larger city than Paris, and that are titled the ''Essays in Political Arithmetick'' by Hull. This group of pamphlets had a close relation to [[John Graunt]]'s ''Observations upon the Bills of Mortality of London.''
* The ''Quantulumcunque concerning Money'' (written in 1682, and printed in 1695, and perhaps in 1682), can probably be considered as belonging to a group of its own.
The division given here was still used by scholars at the end of the twentieth century.<ref name=groups>See for instance for instance {{harv|Hutchison|1988|p=29}} and {{harv|Yang|1994|p=62 (footnote 6)}}. One may wonder why Hull does not mention ''A Treatise of Ireland'' in this list. He was the first to have this manuscript, dated 1687, printed. ({{harvp|Hull|1899|p=545-621}}).</ref>

=== Fiscal contributions ===
By Petty's time, England was engaged in war with Holland, and in the first three chapters of ''Treatise of Taxes and Contributions'', Petty sought to establish principles of taxation and public expenditure, to which the monarch could adhere, when deciding how to raise money for the war. Petty lists six kinds of public charge, namely defence, governance, the ''pastorage of men's souls'', education, the maintenance of ''impotents of all sorts'' and infrastructure, or ''things of universal good''. He then discusses general and particular causes of changes in these charges. He thinks that there is great scope for reduction of the first four public charges, and recommends increased spending on care for the elderly, sick, orphans, etc., as well as the government employment of ''supernumeraries''.

Petty was interested in the extent to which taxes could be raised without inciting rebellion<ref>{{cite book |last1=Goodacre |first1=Hugh |title=The Economic Thought of William Petty: Exploring the Colonialist Roots of Economics |date=2018 |publisher=Routledge |location=Abingdon |pages=46–77}}</ref> On the issue of raising taxes, Petty was a definite proponent of [[consumption tax]]es. He recommended that in general taxes should be just sufficient to meet the various types of public charges that he listed. They should also be horizontally [[Equity (economics)|equitable]], regular and proportionate. He condemned [[Tax per head|poll tax]]es as very unequal and excise on beer as taxing the poor excessively. He recommended a much higher quality of statistical information, to raise taxes more fairly. Imports should be taxed, but only in such a way that would put them on a level playing field with domestic produce. A vital aspect of economies at this time was that they were transforming from [[barter]] economies to money economies. Linked to this, and aware of the scarcity of money, Petty recommends that taxes be payable in forms other than gold or silver, which he estimated to be less than 1% of national wealth. To him, too much importance was placed on money, "which is to the whole effect of the Kingdom… not [even] one to 100".

=== National income accounting ===
In making the above estimate, Petty introduced in the first two chapters of ''Verbum Sapienti'' the first rigorous assessments of [[national income]] and wealth. To him, it was all too obvious that a country's wealth lay in more than just gold and silver. He worked off an estimation that the average personal income was £6 13s 4d per annum, with a population of six million, meaning that national income would be £40m. Petty's theory produced estimates, some more reliable than others, for the various components of national income, including land, ships, personal estates and housing. He then distinguished between the stocks (£250m) and the flows yielding from them (£15m). The discrepancy between these flows and his estimate for national income (£40m) leads Petty to postulate that the other £25m is the yield from what must be £417m of labour stock, the "value of the people". This gave a total wealth for England in the 1660s of £667m.

=== Statistics ===
[[Image:William Petty.png|thumb|right|200px|Sir William Petty]]
Petty's only statistical technique is the use of simple averages. He would not be a statistician by today's standards but during his time a statistician was merely one that employed the use of [[quantitative data]]. Because obtaining census data was difficult, if not impossible, especially for Ireland, he applied methods of [[Estimation theory|estimation]]. The way in which he would estimate the population would be to start with estimating the population of London. He would do this by either estimating it by exports or by deaths. His method of using exports is by considering that a 30 per cent increase in exports corresponds to a similar proportionate increase in population. The way he would use deaths would be by multiplying the number of deaths by 30 – estimating that one out of thirty people dies each year. To obtain the population of all of England he would multiply the population of London by 8. Such a simple use of estimation could have easily have been abused and Petty was accused more than once of [[Forgery|doctoring]] the figures for the Crown. (Henry Spiegel)

=== Money supply and circulation ===
This figure for the stock of wealth was contrasted with a [[money supply]] in gold and silver of only £6m. Petty believed that there was a certain amount of money that a nation needed to drive its trade. Hence it was possible to have too little money circulating in an economy, which would mean that people would have to rely on [[barter]]. It would also be possible for there to be too much money in an economy. But the topical question was, as he asks in chapter 3 of ''Verbum Sapienti'', would £6m be enough to drive a nation's trade, especially if the King wanted to raise additional funds for the war with Holland?

The answer for Petty lay in the [[velocity of money]]'s circulation. Anticipating the [[quantity theory of money]] often said to be initiated by [[John Locke]], whereby economic output (''Y'') times price level (''p'') = money supply (''MS'') times velocity of circulation (''v''), Petty stated that if economic output was to be increased for a given money supply and price level, 'revolutions' must occur in smaller circles (i.e. velocity of circulation must be higher). This could be done through the establishment of a bank. He explicitly stated in ''Verbum Sapienti'' "nor is money wanting to answer all the ends of a well-policed state, notwithstanding the great decreases thereof which have happened within these Twenty years"<ref>''Verbum Sapienti'', p.113</ref> and that higher velocity is the answer. He also mentions that there is nothing unique about gold and silver in fulfilling the functions of money and that money is the means to an end, not the end itself:

<blockquote>Nor were it hard to substitute in the place of Money [gold and silver] (were a comptency of it wanting) what should be equivalent unto it. For Money is but the Fat of the Body-Politick, whereof too much doth often hinder its agility, as too little makes it sick... so doth Money in the State quicken its Action, feeds from abroad in the time of Dearth at home.'<ref>Hull 1899: p.113</ref></blockquote>

What is striking about these passages is his intellectual rigour, which put him far ahead of the [[mercantilism|mercantilist]] writers of earlier in the century. The use of biological analogies to illustrate his point, a trend continued by the [[physiocrats]] in France early in the 18th century, was also unusual.

=== Theory of value ===
On value, Petty continued the debate begun by [[Aristotle]], and chose to develop an input-based theory of value: "all things ought to be valued by two natural Denominations, which is Land and Labour" (p.&nbsp;44). Both of these would be prime sources of [[taxable income]]. Like [[Richard Cantillon]] after him, he sought to devise some equation or par between the "mother and father" of output, land and labour, and to express value accordingly. He still included general [[productivity]], one's "art and industry". He applied his theory of value to rent. The natural rent of a land was the excess of what a labourer produces on it in a year over what he ate himself and traded for necessities. It was therefore the [[Profit (economics)|profit]] above the various costs related to the factors involved in production.

=== Interest rate ===
The natural rate of rent is related to his theories on [[usury]]. At the time, many religious writers still condemned the charging of interest as sinful. Petty also involved himself in the debate on usury and [[interest rate]]s, regarding the phenomenon as a reward for forbearance on the part of the lender. Incorporating his theories of value, he asserted that, with perfect security, the rate of interest should equal the rent for land that the principal could have bought – again, a precocious insight into what would later become general equilibrium findings. Where security was more "casual", the return should be greater – a return for risk. Having established the justification for usury itself, that of [[forbearance]], he then shows his [[Hobbesian]] qualities,{{Explain|date=April 2025}} arguing against any government regulation of the interest rate, pointing to the "vanity and fruitlessness of making civil positive laws against the laws of nature".<ref>''Quantumlumque'', (p.&nbsp;48</ref>{{Failed verification|date=March 2025}}

=== ''Laissez-faire'' governance ===
This is one of the major themes of Petty's writings, summed up by his use of the phrase ''vadere sicut vult'', from which ''[[laissez-faire]]'' is derived. As mentioned earlier, the motif of medicine was also useful to Petty, and he warned against over-interference by the government in the economy, seeing it as analogous to a physician tampering excessively with his patient. He applied this to monopolies, controls on the exportation of money and on the trade of commodities. They were, to him, vain and harmful to a nation. He recognised the price effects of monopolies, citing the French king's salt monopoly as an example. In another work, ''Political Arithmetic'', Petty also recognised the importance of economies of scale. He described the phenomenon of the division of labour, asserting that a good is both of better quality and cheaper, if many work on it. Petty said that the gain is greater "as the manufacture itself is greater".

=== Foreign exchange and control of trade ===
On the efflux of [[money|specie]], Petty thought it vain to try to control it, and dangerous, as it would leave the merchants to decide what goods a nation buys with the smaller amount of money. He noted in ''Quantulumcunque concerning money'' that countries plentiful in gold have no such laws restricting [[money|specie]]. On exports in general, he regarded prescriptions, such as recent Acts of Parliament forbidding the export of wool and yarn, as "burthensome". Further restrictions "would do us twice as much harm as the losse of our said Trade" (p.&nbsp;59), albeit with a concession that he is no expert in the study of the wool trade.

On prohibiting imports, for example from Holland, such restrictions did little other than drive up prices, and were only useful if imports vastly exceeded exports. Petty saw far more use in going to Holland and learning whatever skills they have than trying to resist nature. Epitomizing his viewpoint, he thought it preferable to sell cloth for "debauching" foreign wines, rather than leave the clothiers unemployed.

=== Division of labour ===
In his [http://www.marxists.org/reference/subject/economics/petty/index.htm Political Arithmetick], Petty made a practical study of the [[division of labour]], showing its existence and usefulness in Dutch shipyards. Classically the workers in a shipyard would build ships as units, finishing one before starting another. But the Dutch had it organised with several teams each doing the same tasks for successive ships. People with a particular task to do must have discovered new methods that were only later observed and justified by writers on [[political economy]].

Petty also applied the principle to his survey of Ireland. His breakthrough was to divide up the work so that large parts of it could be done by people with no extensive training.

=== Urban society ===
Petty projected the growth of the city of London and supposed that it might swallow the rest of England – not so far from what actually happened:
<blockquote>
Now, if the city double its people in 40 years, and the present number be 670,000, and if the whole territory be 7,400,000, and double in 360 years, as aforesaid, then by the underwritten table it appears that A.D. 1840 the people of the city will be 10,718,880, and those of the whole country but 10,917,389, which is but inconsiderably more.  Wherefore it is certain and necessary that the growth of the city must stop before the said year 1840, and will be at its utmost height in the next preceding period, A.D. 1800, when the number of the city will be eight times its present number, 5,359,000.  And when (besides the said number) there will be 4,466,000 to perform the tillage, pasturage, and other rural works necessary to be done without the said city.<ref>OF THE GROWTH OF THE CITY OF LONDON – among the essays downloadable at the Gutenberg link.</ref>
</blockquote>

He imagined a future in which "the city of London is seven times bigger than now, and that the inhabitants of it are 4,690,000 people, and that in all the other cities, ports, towns, and villages, there are but 2,710,000 more". He expected this some time around 1800, [[extrapolating]] existing trends. Long before [[Thomas Malthus|Malthus]], he noticed the potential of the human population to increase. But he also saw no reason why such a society should not be [[Prosperity|prosperous]].

==Legacy==
Petty is best remembered for his [[economic history]] and statistical writings, preceding the work of [[Adam Smith]], and for being a founding member of the Royal Society. Of particular interest were his forays into [[statistical analysis]]. Petty's work in political arithmetic, along with the work of [[John Graunt]], laid the foundation for modern census techniques. This work in statistical analysis, when further expanded by writers like [[Josiah Child]] documented some of the first expositions of modern insurance. [[Vernon Louis Parrington]] notes him as an early expositor of the [[labour theory of value]] as discussed in ''Treatise of Taxes'' in 1692.<ref>{{cite book |last1=Parrington |first1=Vernon Louis |url=http://xroads.virginia.edu/~Hyper/Parrington/vol1/bk02_01_ch03.html |archive-url=https://web.archive.org/web/20060819092443/http://xroads.virginia.edu/~Hyper/Parrington/vol1/bk02_01_ch03.html |url-status=dead |archive-date=19 August 2006 |title=The Colonial Mind, 1620–1800 |last2=Levy |first2=David W. |volume=1}}</ref>

He influenced several future economists, including [[Richard Cantillon]], [[Adam Smith]], [[Karl Marx]], and [[John Maynard Keynes]]. Petty and Adam Smith shared a worldview that believed in a harmonious natural world.  They both saw the benefits of specialisation and the [[division of labour]]. Smith said nothing about Petty in ''[[The Wealth of Nations]]''. In his published writings, there is nothing apart from a reference in a letter to [[Lord Shelburne]], one of Petty's aristocratic descendants.<ref>''Correspondence of Adam Smith'', Letter No. 30, Glasgow Edition</ref>

Karl Marx imitated Petty's belief that the total effort put in by the aggregate of ordinary workers represented a far greater contribution to the economy than contemporary ideas recognised. This belief led Petty to conclude that labour ranked as the greatest source of wealth. By contrast, Marx's conclusions were that [[surplus labour]] was the source of all [[Profit (economics)|profit]], and that the labourer was [[Marx's theory of alienation|alienated]] from his surplus and thus from society. Marx's high esteem of Adam Smith is mirrored in his consideration of Petty's analysis, testified for by countless quotations in his major work ''[[Das Kapital]]''. [[John Maynard Keynes]] demonstrated how governments could manage [[aggregate demand]] to stimulate output and employment, much as Petty had done with simpler examples in the 17th century. Petty's simple £100-through-100-hands multiplier was refined by Keynes and incorporated into his model.

Some consider Petty's achievements a matter of good fortune. Petty was a music professor before being apprenticed to the brilliant [[Thomas Hobbes]]. He arrived upon his laissez-faire view of economics at a time of great opportunity and growth in the expanding British Empire. Laissez-faire policies stood in direct contrast to his supervisor Hobbes's [[Social Contract]], developed from Hobbes's experiences during the greatest depression in England's history, [[the General Crisis]].

=== Monument ===
In 1858 [[Henry Petty-Fitzmaurice, 3rd Marquess of Lansdowne]], one of Petty's descendants, erected a memorial and likeness of Petty in [[Romsey Abbey]]. The text on it reads: "A true patriot and a sound philosopher who, by his powerful intellect, his scientific works and indefatigable industry, became a benefactor to his family and an ornament to his country". A monumental slab on the floor of the south choir aisle of the Abbey reads "HERE LAYES SIR WILLIAM PETY". The third Marquess also erected the [[Lansdowne Monument]] on Cherhill Down in Wiltshire.

==Publications==
* 1647: ''[[The Advice to Hartlib]]''
* 1648: ''[[Double Writing (Petty)|A Declaration Concerning the newly invented Art of Double Writing]]''
* 1659: ''[[Proceedings between Sankey and Petty]]''
* 1660: ''[[Reflections upon Ireland]]''
* 1662: ''[[A Treatise of Taxes & Contributions]]'' (later editions: 1667, 1679, 1685, etc.)
* ''Political Arithmetic'' posthum. (approx. 1676, pub. 1690)
* ''Verbum Sapienti'' posthum. (1664, pub. 1691)
* ''Political Anatomy of Ireland'' posthum. (1672, pub. 1691)
* ''Quantulumcunque Concerning Money'' ("something, be it ever so small, about money")<ref>Translation by Strathern 2001</ref> posthum. (1682, pub. 1695)<ref>[[Image:wikisource-logo.svg|16x16px|alt=wikisource logo]] ''[[:s:en:Quantulumcunque concerning Money (Petty 1682)|Quantulumcunque]]'' in: [[:s:en:The Economic Writings of Sir William Petty/Volume 2|''The Economic Writings of Sir William Petty'' (vol. 2)]] (1899).</ref>
* ''An Essay Concerning the Multiplication of Mankind''. (1682)

==Notes==
{{notelist}}

==References==
{{Reflist}}

==Sources==
* [[Svit Komel|Komel, Svit]] (2024) "Petty's instruments: the Down Survey, territorial natural history and the birth of statistics" in ''The British Journal for the History of Science 57 (1)'': 43–64 | url = https://www.cambridge.org/core/journals/british-journal-for-the-history-of-science/article/pettys-instruments-the-down-survey-territorial-natural-history-and-the-birth-of-statistics/0C35B4A6C753DE4DF81B523B4AD6B62B#article.
* [[Tony Aspromourgos|Aspromourgos, Tony]] (1988) "The life of William Petty in relation to his economics" in ''History of Political Economy 20'': 337–356.
* {{Cite book|last1=Burke |first1=John |last2=Burke |first2=Sir Bernard |year=1844 |title=A Genealogical and Heraldic History of the Extinct and Dormant Baronetcies of England, Ireland and Scotland |edition=2 |publisher=J. R. Smith |page=605 |chapter=Fenton of Mitchelstown|chapter-url=https://books.google.com/books?id=DjIGAAAAQAAJ&pg=PA605}}
* {{cite book|author=Eli F. Heckscher|title=Mercantilism|url=https://books.google.com/books?id=RXX5AQAAQBAJ|date=2013|orig-year=1935|volume=1|publisher=Taylor & Francis|isbn=978-1-136-15738-7}}
* {{cite book | last = Hutchison | first = Terence | author-link = Terence Wilmot Hutchison
| date = 1988
| title = Before Adam Smith : The Emergence of Political Economy, 1662-1776
| url = https://archive.org/details/beforeadamsmithe0000hutc | url-access = registration | location = Oxford / New York | publisher =  Basil Blackwell | language = en
| isbn = 0-631-15898-7 }}
* {{cite wikisource |editor-last=Hull |editor-first=Charles Henry |editor-link=Charles Henry Hull
|date=1899
|title=The Economic Writings of Sir William Petty; together with the Observations upon the Bills of Mortality, more probably by Captain John Graunt
|wslink=The Economic Writings of Sir William Petty
|location=Cambridge
|publisher=[[Cambridge University Press]]
|id={{OCLC |803827975}} |ol=4007495W }}
* [[Terence Wilmot Hutchison|Hutchison, Terence]] (1988). "Petty on Policy, Theory and Method," in ''Before Adam Smith: the Emergence of Political Economy 1662–1776''. Basil Blackwell.
* {{cite book|author=William Letwin|author-link=William Letwin|title=The Origins of Scientific Economics|url=https://books.google.com/books?id=ee77AQAAQBAJ|date=2013|orig-year=1963|publisher=Routledge|isbn=978-1-136-50864-6}}
* {{cite book|first=Ted |last=McCormick|title=William Petty And the Ambitions of Political Arithmetic|url=https://books.google.com/books?id=Ag4UDAAAQBAJ|date=2009|publisher=Oxford University Press|isbn=978-0-19-954789-0}}
* [[Guy Routh|Routh, Guy]] (1989) ''The Origin of Economic Ideas''. London: Macmillan.
* {{cite book|author=Joseph A. Schumpeter|author-link=Joseph Schumpeter|title=History of Economic Analysis|url=https://books.google.com/books?id=pl4DABZfGREC|date=2006|orig-year=1954|publisher=Routledge|isbn=978-1-134-83870-7}}
* Strathern, Paul (2001) - ''Dr Strangelove's Game : a brief history of economic genius''. London : Hamish Hamilton.
* {{cite book | last = Yang | first = Hong-Seok
| title = The Political Economy of Trade and Growth: An Analytical Interpretation of Sir James Steuart's Inquiry
| date = 1994
| publisher =  Edward Elgar
| isbn = 9781782543619
| url = https://books.google.com/books?id=LDuNeTqxODoC }} (especially section 'Petty's Natural Price', pp.&nbsp;61–68)

==External links==
{{wikisource|works=or}}
* [http://socserv2.socsci.mcmaster.ca/~econ/ugcm/3ll3/petty/index.html Archive for the History of Economic Thought: "William Petty"] {{Webarchive|url=https://web.archive.org/web/20171105053842/http://socserv2.socsci.mcmaster.ca/~econ/ugcm/3ll3/petty/index.html |date=5 November 2017 }}
* {{Gutenberg author | id=1815}}
* {{Internet Archive author |sname=William Petty}}
* [http://www.marxists.org/reference/subject/economics/petty/index.htm Political Arithmetick (3rd Edition, 1690]
* [https://web.archive.org/web/20051210065554/http://www.bowood-house.co.uk/pdf/LansdowneFamilyTree.pdf Petty FitzMaurice (Lansdowne) family tree]
* [[National Portrait Gallery (United Kingdom)|National Portrait Gallery]] has five portraits of Sir William Petty: [http://www.npg.org.uk/live/search/ Search the collection] {{Webarchive|url=https://web.archive.org/web/20061219023458/http://www.npg.org.uk/live/search/ |date=19 December 2006 }}
* [http://www.punkerslut.com/critiques/petty/treatise.html Critique of "A Treatise of Taxes and Contributions"] {{Webarchive|url=https://web.archive.org/web/20160303215804/http://www.punkerslut.com/critiques/petty/treatise.html |date=3 March 2016 }}
* [http://www.kenmare.com/history/ Kenmare Journal – A Bridge to the Past.] {{Webarchive|url=https://web.archive.org/web/20191228014326/http://www.kenmare.com/history/ |date=28 December 2019 }}

{{Mercantilists}}

{{Authority control}}

{{DEFAULTSORT:Petty, William}}
[[Category:William Petty| ]]
[[Category:1623 births]]
[[Category:1687 deaths]]
[[Category:17th-century English medical doctors]]
[[Category:17th-century English male writers]]
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[[Category:People from Romsey]]
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[[Category:17th-century English businesspeople]]
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[[Category:Founder fellows of the Royal Society]]
[[Category:Alumni of the University of Oxford]]
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[[Category:Petty-Fitzmaurice family|William]]
[[Category:Mercantilists]]
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