Front Page Titles (by Subject) [CHAPTER I.]: OF POPULATION CONSIDERED AS AN ARTICLE OF THE NATURAL HISTORY OF MAN. - Lectures on Political Economy, vol. 1
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[CHAPTER I.]: OF POPULATION CONSIDERED AS AN ARTICLE OF THE NATURAL HISTORY OF MAN. - Dugald Stewart, Lectures on Political Economy, vol. 1 
Lectures on Political Economy. Now first published. Vol. I. To which is Prefixed, Part Third of the Outlines of Moral Philosophy, edited by Sir William Hamilton (Edinburgh, Thomas Constable, 1855).
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OF POPULATION CONSIDERED AS AN ARTICLE OF THE NATURAL HISTORY OF MAN.
The propagation of animals, and the circumstances on which it depends, are among the most interesting subjects of inquiry in the whole economy of Nature; and when considered in their relation to the physical necessities and the moral habits of different tribes, exhibit the most striking evidences of wise and benevolent design. On this subject, however, I do not mean to enlarge, but shall content myself with referring to Buffon and the other writers on Natural History, for an illustration of the beautiful arrangements which are conspicuous in the general laws here presented to our observation.
The propagation of all animals supposes a competency of that kind of food on which the particular tribe is destined to subsist. This provision being equal, the rate at which the multiplication of different races would go, seems to depend on the following particulars:1 —(1.) The age at which the parent becomes prolific; (2.) The time that elapses in pregnancy; (3.) The frequency of breeding; (4.) The numbers of each brood; and (5.) The period during which the parent continues prolific.
The laws of propagation in our own species appear to vary to a certain extent in different climates; and the general opinion is, that they are most favourable to population in the warmer regions,—a difference, however, which must be partly ascribed to the greater abundance of the means of subsistence. The fact unquestionably is, that nations in those climates are populous, even under great defects of government.
M. Moheau, a French author of extensive and accurate information, assures us that the truth of this general observation with respect to the effects of climate is confirmed by facts, which may be collected within the comparatively narrow limits of France. Other circumstances being the same, the women in the north of France are (according to him) less fruitful than in the south. The same author adds, (upon documents which he thinks entitled to credit,) that whilst in France forty-eight marriages produce at an average two hundred and thirty-two births, the same number of marriages, towards the fifty-second or fifty-third degree of latitude, produce only one hundred and ninety-five births; and beyond the fifty-sixth degree, not more than one hundred and sixty.1 On so very nice a question, however, the results still require to be verified by farther observations.
Without entering more particularly into this speculation, it is sufficient for our purpose to remark, that in all the habitable parts of the globe, the laws of propagation are sufficient for preserving the race and adding to its numbers, provided other circumstances be not unfavourable. In some situations in which the prolific powers of the two sexes have been less restrained than they generally are by the difficulty of rearing a family, the multiplication of the species has been found to be astonishingly rapid. In some parts of America, before the Revolution, the number of inhabitants (according to Franklin) was doubled every fifteen years; in others, every twenty-five years. Nor was this owing to the influx of new inhabitants, but to the actual increase of the people. Those who lived to old age frequently saw from fifty-six to one hundred, and sometimes many more, descendants from their own body. The truth is, that marriage, which in this part of the world is a source of so much expense and anxiety to men of middling fortunes, as to deter many from thinking of that connexion, was in America one of the most effectual steps towards prosperity and affluence. The labour of each child before it could leave its father’s house, was (according to Mr. Smith) computed in some parts of the Continent to be £100 clear gain to him; so that a young widow with four or five children was commonly courted as a sort of fortune.
As the rapid progress of population in the English North American Colonies, is probably without parallel in history, it may be proper to state the fact a little more particularly.
The original number of persons who had settled in the four provinces of New England in 1643, was 21,200. Afterwards, it is supposed, that more left them than went to them. In the year 1760, they were increased to half a million. They had, therefore, all along doubled their own number in twenty-five years. In New Jersey, the period of doubling appears to be twenty-two years; and in Rhode Island still less. In the Back Settlements, where the inhabitants applied themselves solely to agriculture, and luxury was not known, they were found to double their number in fifteen years.1
The operation of similar causes has produced similar effects, although in a very inferior degree, in all the other European settlements in the New World. The truth is, that an abundance of rich land, to be had for little or nothing, is so powerful an encouragement to population as to overcome all obstacles. No settlements could well have been worse managed than those of Spain in Mexico, Peru, and Quito; yet under all their disadvantages these colonies multiplied very rapidly. The city of Lima, founded since the Conquest, is represented by Ulloa as containing fifty thousand inhabitants near fifty years ago. Quito, which had been but a hamlet of Indians, is represented by the same author as in his time equally populous. Mexico is said to contain a hundred thousand inhabitants, which is a number probably five times greater than what it contained in the time of Montezuma.—Nor is this rapid multiplication of the species peculiar to new colonies. It is experienced in every instance in which the numbers of the people fall greatly short of what their means of subsistence might support. It has been often exemplified in Flanders, where the effects of those wars, of which that fertile and beautiful province has so long been the occasional seat, have always been obliterated by a few years of peace. It was exemplified in London, after the fatal plague of 1666, the traces of which, in the short period of twenty years, were scarcely perceptible. The same observation has been made with respect to the effects of the famines in China and Hindostan, and of the plagues which so frequently sweep men by thousands from the face of the earth in Egypt and Turkey.
If this rapid increase was to go on unchecked, it is easy to perceive, that the world would, at no very distant period, be overstocked with inhabitants. Dr. Wallace, in his Dissertation on the Numbers of Mankind, has shewn that this must have been the case long before the Deluge, even on the very moderate supposition, that the numbers of mankind had doubled every thirty-three and one-third years. His computations on this subject deserve attention, as they lead to important consequences.
Suppose, then, the race to begin with a single pair, that all marry who attain to maturity, and that every marriage produces six children, three males and as many females; two of whom (one male and one female) die before marriage, (according to which hypothesis four will remain to marry and replenish the world,) that in thirty-three and one-third years from the time when the original pair began to propagate, they shall have produced their six children; and that within the second period of thirty-three and one-third years, each of the succeeding couples shall have produced six children, and this to take place continually. On these suppositions, at the beginning of the scheme, the original pair alone are in life; at the end of the first period of thirty-three and one-third years, there are six persons living, viz., the original pair and four others; at the end of sixty-six and two-third years, there will be twelve; at the end of one hundred years, there will be twenty-four living; and at the end of twelve hundred years, (the numbers of mankind continuing to double every thirty-three and one-third years,) the number alive will be 206,158,430,208. According to the computations of the same very learned and ingenious writer, the whole habitable earth does not actually contain, at this moment, more than one thousand millions.
From the facts already stated with respect to our colonies in North America, it appears to be abundantly confirmed by actual experience, that even in circumstances which by no means afforded to the prolific powers of our species their greatest conceivable scope, population has gone on doubling itself every twenty-five years.
Assuming this, therefore, as a general rule, (which is obviously far short of the truth,) that population, when unchecked, goes on doubling itself every twenty-five years, a late anonymous author* argues in the following manner:—
“Suppose the restraints to population, all over the earth, to be completely removed, and consider in what ratio the subsistence it affords can be conceived to increase. If it were to be increased every twenty-five years by a quantity equal to what the whole world at present produces; this would allow the power of production in the earth to be absolutely unlimited, and the rate of its increase much greater than we can imagine any possible exertions of mankind to make it.
“Taking the population of the world at any number, a thousand millions for instance, the human species would increase in the ratio of—1, 2, 4, 8, 16, 32, 64, &c.; [a Geometrical ratio.] And subsistence as—1, 2, 3, 4, 5, 6, 7, &c.; [an Arithmetical ratio.] In two centuries and a quarter, the population would be to the means of subsistence as 512 to 10; in three centuries, as 4096 to 13; and in two thousand years, the difference would be almost incalculable, though the produce in that time would have increased to an immense extent.”
From this reasoning, which seems to be just in the main, it may be fairly inferred, that although the rapid multiplication of our species be in some states of society incomparably greater than in others, it does not appear to be a part of the order of Providence, that this rapidity should continue or be universal, an insurmountable obstacle being opposed to it by the other physical arrangements of our globe.
These considerations are sufficient, of themselves, to suggest a doubt, How far it is true that a rapidly increasing population is an unequivocal test of a wisely constituted government; and, Whether the mere increase of numbers ought to be a leading object of attention to a legislator. That both of these questions are to be answered in the affirmative, under proper limitations, is beyond dispute; but we may, perhaps, find reason afterwards to conclude, that they have been generally discussed by politicians in too vague and unqualified a form. Within these few years, indeed, the connexion between Population and National Prosperity has been examined with much greater accuracy than before, but not perhaps in such a manner as to unite completely the opinions of speculative politicians in their general conclusions. The very ingenious and intelligent author of L’Ami des Hommes, [Mirabeau, the Father,] appears to have wavered a little in his speculations on this point. In the first part of that work he maintains the superiority of National Wealth to Population, and insists that the latter ought to be regarded only as a secondary object by the statesman. But in the second part1 he asserts that Wealth is an inferior object to Population, and that numbers of people are alone the cause of riches.2
Mr. Arthur Young, in his Political Arithmetic, (published in 1774,) lays it down as a most important and fundamental principle, that Population should be ever regarded as subordinate to Agriculture. “If a measure,” says he, “is beneficial to the latter, give no attention to those who talk of injuring population. If you act primarily from an idea of encouraging populousness, you may injure husbandry; but if your first idea is the encouragement of the latter, you cannot reduce population below that standard which, being adapted to the circumstances of the country, can alone render it a source of national strength and of general happiness.”1
Before, however, I enter on these discussions, it is necessary for me to consider, on what political causes the population of a country depends;—an inquiry of great extent and importance, and which (in the manner I propose to treat it) will lead to an examination of some of the most interesting articles of Political Economy. The slight reference which I have just now made to the speculations of the Marquis de Mirabeau and of Mr. Young, is sufficient to shew how very intimately the different branches of this science are connected together.
[1 ] Ferguson’s Institutes [of Moral Philosophy.]
[1 ]Recherches sur la Population de la France, [1778,] p. 139. It is curious that Mr. Hume seems to lean to the contrary idea, and to suppose that women are more prolific in the northern regions. [See his Essay on the Populousness of Antient Nations, and the adverse quotation from Columella.]
[1 ]Essay on the Principle of Population. [Malthus,—first edition of his Essay in 1798,] p. 105.
[* ] [Mr. Malthus is here referred to: At the time (c. 1800) when these Lectures were originally written, the Essay on the Principle of Population had been only anonymously published, in 1798. The second edition, with the author’s name, and the reasoning considerably modified, appeared in 1803; and in Mr. Stewart’s subsequent courses, (as is seen from the fragment extant of a lecture in 1804, and from the notes taken in 1809, by Mr. Bridges and others,) Mr. Malthus is explicitly quoted.—See infra, pluries.]
[1 ] See the letters annexed to Socrate Rustique, (by M. Hirzel of Zurich,) translated by Arthur Young in his Rural Economy.
[2 ] Of this contradiction Mirabeau himself takes notice, in a letter addressed to the French translator of a German Treatise entitled The Rural Socrates. “I have always,” says he, “been scrupulous of making alterations in the Essays I publish, if they go through a second edition; though certainly in one of them there is a very essential correction wanting; for, in second part of L’Ami des Hommes, [1755,] I have expressly contradicted what I asserted as a fundamental principle in the first—That Population was the consequence of Riches; I was sensible of my error in mistaking the cause for the effect, and have since advanced that Riches are the consequence of Population. The method was simple and easy to have established this latter opinion by some slight additions, explaining the principles on which it is founded; but I was unwilling to lessen the value of the book to the first purchasers, and have invariably persisted in not changing the least sentence in the works once published; or adding anything by way of Appendix, in future editions.”—See Addenda to Socrate Rustique. Translated by A. Young, [in his Rural Economy, 1770.]
[1 ] See Political Arithmetic, pp. 264-267. In the last sentence of the above quotation, I have departed a little from Mr. Young’s words; but the limitation I have added seems to be absolutely necessary for conveying his idea fully.