William Petty

“ In other words he pursued the method of political arithmetic as distinguished from statistics. Statistics demands enumeration. The validity of its inferences depends upon the theory of probabilities as expressed in the Law of Large Numbers. Therefore it adds, it does not multiply. Political arithmetic, as exemplified by Petty, multiplies freely; and the value of its results varies according to the nature of the terms multiplied. For example, in the absence of a census Petty had to calculate the population of London, of England, and of Ireland. ”

“ The death of the Lord Protector had reanimated the purely parliamentarian party of the army in England to an activity that boded no good to his sons. Petty was, throughout his life, a firm supporter of the family of Cromwell, and it was as Henry Cromwell's friend that he had been elected member for West Looe in Richard's parliament. It is not surprising, therefore, that the charges of bribery and breach of trust now preferred against him in the House of Commons by Sir Jerome Sanchey [23] should have appeared to the officers at Dublin as a blow struck at the Lord Deputy himself. ”

“ In order therefore that legal provision should be made, and that money should be forthcoming, for their ascertainment, it was first necessary that the value of possible statistical deductions from accurate data should be demonstrated by the intelligent use of those sparse materials which lay ready to the student's hand. It is in this sense that we must judge the essays of Graunt and Petty, which pioneered the way of modern statistics, and so judged they will be found worthy of high praise. ”

“ The economic method which Petty chiefly pursued, taken in combination with the limited extent of his materials, of necessity confined him to the discussion of a few out of the many questions that must have thronged upon his active mind. In no other field of economic interest were so many figures available as in that of taxation, and the fiscal changes of the Restoration, chancing to come just at the time when he first had leisure to return to his studies, gave to his economic inquiries a direction from which he never wholly departed. ”

“ Those who have agreed that Graunt was the author of the "Observations," need not leave to their opponents the exclusive use of internal evidence. They, for their part, may first point out that there are considerable differences of language between Petty's works and Graunt's [40] . Every one at all familiar with seventeenth-century English pamphlets has sympathized with Sir Thomas Browne's solicitude lest "if elegancy still proceedeth, and English pens maintain that stream, which we have of late observed to flow from many, we shall within few years be fain to learn Latin to understand English." ”

“ As statistical writing Graunt's "Observations upon the Bills of Mortality" are superior to any of Petty's works. Indeed they alone can claim to be "statistics"; Petty's "Essays" are so different in character that his own name of "political arithmetick" is still their most accurate description. The difference, as has been pointed out [1] , arises in part rather from Graunt's sparing use of calculation than from any especial merit in such calculations as he does make. His estimate of London's population [2] is superior to Petty's in no way unless it be by reason of priority ”

“ Nowhere does Petty appear to greater advantage than in his letters to his wife, and her letters to him fully bear out Evelyn's judgment, "she was an extraordinary wit as well as beauty and a prudent woman." ”

“ In his economic writings too there are traces of Hobbes's influence, but it is—if the distinction be admissible—upon Petty as a politician rather than upon Petty as an economist that his influence was chiefly exerted. It appears most strikingly in the assumption that the government is justified in doing anything by which the national wealth can be increased. Again and again Petty advocates sweeping public measures which take no account whatever of the rights and sensibilities of the citizen. ”

“ To determine the mere number of persons who died, or were born or married, is much less difficult than to determine the causes of their death; but even in the former respects the seventeenth century bills leave much to be desired. Graunt himself pointed out "that there hath been a neglect in the Accompt of the Christenings [68] ," and explains that this "hath been neglected more than that of Burials" because religious scruples played a larger part in the former case [69] . But even the record of burials included, as a rule, only those buried according to the service of the Church of England. ”

“ But every man not wholly erratic is at once impelled by his circumstances and restrained by his training. Postulate these, and you may discover in his actual course some trace of the mean orbit which calculation would predict.
The inspiration of Petty's writings is not far to seek. Written before the days of formal treatises on political economy, they are neither the systematized abstractions of a metaphysician condescending to every-day affairs, nor the less systematic but no less abstract arguments of a man of affairs with an undisciplined bent toward speculative thinking. ”

“ But there is a note of sincerity very characteristic of the man in the confession of faith with which he closed his will: "As for religion, I dye in the profession of that faith, and in the practice of such worship, as I find established by the Law of my country, not being able to believe what I myself please, nor to worship God better than by doing as I would be done unto, and observing the Laws of my country, and expressing my love and honour to Almighty God by such signes and tokens as are understood to be such by the people with whom I live, God knowing my heart even without any at all." ”

“ How great the error due to this fact may have been in the seventeenth century, we have no means of knowing. In the middle of the eighteenth it was very plausibly calculated at one sixth of the whole number [73] . Taking all these facts into account, it is not too much to assume that we must add a correction of at least fifteen per cent. to the figures of burials in the pre-Restoration bills, and not less than ten per cent. to the later figures which Petty uses, in order to obtain an approximately correct estimate of the actual mortality of London at the dates in question. ”

“ In general, the probabilities strongly favour Graunt. In the first place, he was a citizen and a native of London. He thus had opportunity to collect the bills and incentive to study them; and the author's account of the way in which he came to make the study tallies in every particular with the known facts of Graunt's life. Petty, on the other hand, was of provincial birth, and had been a resident of London but a short time when the "Observations" were published. In the second place, the "Observations" are not the product of a few leisure hours, or even of a few hurried weeks. ”

“ He seems in the mean time to have changed his opinion of "people who make use of titles and tools" and accordingly he made a journey to London, apparently with the intention of securing both the title and the seat at the Council table [76] . But Charles II. answered the protestants that by their good leave he would chose his own council for Ireland, and Petty fearing that "a bare title without some trust might seem to the world a body without soul or spirit [77] ," declined the peerage for a second time. ”

“ It is improbable that even Petty, in spite of the openness of his mind and the vigour of his imagination, appreciated to the full the significance of Graunt's discoveries; but it may perhaps be noted that he wrote of another great work of his day, "Poor Mr Newton... I have not met with one man that putt an extraordinary value on his book. ”

“ The general trustworthiness of the bills, and consequently the validity of all conclusions based upon them, is conditioned by the accuracy and the completeness with which the Parish Clerks knew the facts that they professed to report. It is therefore important to enquire how they obtained their knowledge of the number of christenings, marriages, and burials and of the causes of death within their respective parishes. The earliest indication of the method pursued is found in the plague orders of the Lord Mayor, issued in 1581. ”

“ In the third place, it deserves to be noted that the chief parallels to Petty's writings do not occur in parts of the "Observations" which are vital or organic. In his patient investigations of the movement of London's population, imperfect and frequently erroneous though they were, and, for lack of data, necessarily must have been, the author of the "Observations" displays admirable traits for which Petty's writings, however meritorious otherwise, may still be searched in vain. ”

“ Consequently the number of the people, which becomes in the "Verbum Sapienti" (1664) a key to the national wealth, and thus affords a basis for the distribution of taxation much more satisfactory than expenditure [46] , is used in the "Treatise" but incidentally to a minor question of retrenchment [47] .
To the problem of national wealth Petty never tires of applying the methods of his political arithmetic. The "Verbum Sapienti" shows both the reason that led him to attack the problem and the method which he employed for its solution. ”

“ The spirit of their work is often different when no question of calculation enters. Petty sometimes appears to be seeking figures that will support a conclusion which he has already reached: Graunt uses his numerical data as a basis for conclusions, declining to go beyond them [4] . He is thus a more careful statistician than Petty, but he is not an economist at all.
Some of the most important facts which the study of vital statistics has yet discovered were first brought to light by Graunt. ”

“ He was known as a great peacemaker and was often chosen an arbitrator between disputing merchants. He had, before the completion of his thirtieth year, sufficient influence to secure for his friend Petty the professorship of music at Gresham College [7] , and at the time of the Fire he had become "an opulent merchant of London, of great weight and consideration in the city [8] ." So much, in large part but inference, it is still possible to collect concerning the earlier career of John Graunt, citizen and draper. ”

“ His book, with all its faults, deserves a place among the penetrating and fearless treatises which, marred though they were by much now known to be absurd, still contributed to render even the early years of the Royal Society illustrious. ”

“ The protestant colonists prospered in trade, as he had observed the heterodox everywhere to do [58] , and Kenmare clearly demonstrated what thrift, backed by sufficient capital and directed by conspicuous shrewdness, could do for the real settlement of Ireland even under Charles II. After the accession of James II. the colonists fell victims to the jealousy of the surrounding Irish, whose violence was encouraged by Tyrconnel's policy, and thus the most successful of Petty's numerous experiments finally came to naught [59] . ”

“ In other words a man vested with magisterial powers is morally justified in using them as his conscience dictates. But Petty himself is far from thinking it either necessary or expedient to use such powers to secure uniformity of worship. On the contrary he warmly commends the heterodox, though with curious reservations lest by going too far he give offence [11] , and he regards dissent as not only harmless but inevitable. ”

“ As Petty's stake in the prosperity of Ireland grew larger, his interest in the affairs of the kingdom likewise increased. He had been a member of the Irish parliament of the Restoration [60] and one of the commissioners appointed to execute the Act of Settlement, he had taken a prominent part in opposing the bill which prohibited the importation of Irish cattle into England [61] , and he had even attempted, though apparently quite ignorant of the law, to fill the position of a judge of admiralty ”

“ A favoured economist like Von Thünen—with whose aims Petty's thought exhibits much affinity though he lacks Von Thünen's conspicuous patience—may make similar experiments upon a small scale. Most of us, however, must get on as best we may without any economic laboratory whatever. In this respect Petty was no exception. Experiment being impossible, he substituted what he called Political Arithmetick, a beginning of what is now called statistics. ”

“ For "no man can believe what himself pleases and to force men to say they believe what they do not, is vain, absurd, and without honour to God." Besides "where most indeavours have been used to help Uniformity, there Heterodoxy hath most abounded [15] ." The best policy therefore is for the government to pluck with moderation the geese who persist in their unauthorized beliefs [16] .
Upon Petty as an economist the influence of Hobbes was far outweighed by that of Bacon. ”

“ The possibility of an official vindication being thus precluded, Petty resolved to carry his case before the bar of public opinion. With this end in view he published a succinct account of the dispute with Sanchey down to 13 July, 1659 [28] and the succeeding year he followed it up with a volume of nearly two hundred pages [29] describing the work of survey and distribution, answering the charges brought against him, and explaining how they arose "from the envy and hatred of several parties promiscuously" and "from particular designing persons and parties" in Ireland. ”

“ Income [65] being with Petty the starting point for estimating wealth, he feels the necessity of explaining those sorts of income—rent and interest— which do not result evidently from current labour. Now the fundamental question arising alike in a theory of rent and in a theory of interest is this: why does the right to receive a definite annual payment throughout an infinite succession of years command in the market only a finite sum? ”

“ The first additional matter of importance was the specification of those casualties and diseases, other than the plague, which resulted in death. According to Graunt the causes of non-plague burials were ascertained and entered in the Hallbooks "in the very first year [50] ." Bell likewise says that the parishes within the walls, "ever since the year 1604, brought to the Company of Parish Clerks Hall, not only the number of all the christenings and burials, but also an accompt of all the diseases and casualties, although no such accompt was published to the world until the Year 1629." ”

“ But the powerful influence of Essex, whom Temple charges with intriguing for a reappointment to the Lord Lieutenancy, was thrown in Shaen's favour. Petty was represented by some to be a conjurer and by some to be notional and fanciful near up to madness [80] , the needs of the Exchequer were urgent, and the plan that promised ready cash was adopted. Deeply disappointed, Petty returned to Ireland in the summer of 1683 and solaced himself with a journey into Kerry, and presently with a renewal of the experiments that had occupied his mind some twenty years before [81] . ”