An Essay on the Principle of Population

The havoc made by war in the smaller states of Italy, particularly during the first struggles of the Romans for power, seems to have been still greater than in Greece. Wallace, in his Dissertation on the Numbers of Mankind, after alluding to the multitudes which fell by the sword in these times, observes, “On an accurate review of the history of the Italians during this period, we should wonder how such vast multitudes could be raised as were engaged in those continual wars till Italy was entirely subdued.”
*13 And Livy expresses his utter astonishment that the Volsci and Æqui, so often as they were conquered, should have been able to bring fresh armies into the field.
*14 But these wonders will perhaps be sufficiently accounted for, if we suppose, what seems to be highly probable, that the constant drains from wars had introduced the habit of giving nearly full scope to the power of population; and that a much larger proportion of births, and of healthy children were rising into manhood and becoming fit to bear arms, than is usual in other states not similarly circumstanced. It was, without doubt, the rapid influx of these supplies, which enabled them, like the ancient Germans, to astonish future historians, by renovating in so extraordinary a manner their defeated and half-destroyed armies.

Yet there is reason to believe that the practice of infanticide prevailed in Italy as well as in Greece from the earliest times. A law of Romulus forbad the exposing of children before they were three years old,
*15 which implies that the custom of exposing them as soon as they were born had before prevailed. But this practice was of course never resorted to, unless when the drains from wars were insufficient to make room for the rising generation; and consequently, though it may be considered as one of the positive checks to the full power of increase, yet, in the actual state of things, it certainly contributed rather to promote than impede population.

Among the Romans themselves, engaged as they were in incessant wars from the beginning of their republic to the end of it, many of which were dreadfully destructive, the positive check to population from this cause alone must have been enormously great. But this cause alone, great as it was, would never have occasioned that want of Roman citizens under the emperors which prompted Augustus and Trajan to issue laws for the encouragement of marriage and of children, if other causes, still more powerful in depopulation, had not concurred.

When the equality of property, which had formerly prevailed in the Roman territory, had been destroyed by degrees, and the land had fallen into the hands of a few great proprietors, the citizens, who were by this change successively deprived of the means of supporting themselves, would naturally have no resource to prevent them from starving, but that of selling their labour to the rich, as in modern states: but from this resource they were completely cut off by the prodigious number of slaves, which, increasing by constant influx with the increasing luxury of Rome, filled up every employment both in agriculture and manufactures. Under such circumstances, so far from being astonished that the number of free citizens should decrease, the wonder seems to be that any should exist besides the proprietors. And in fact many could not have existed but for a strange and preposterous custom, which, however, the strange and unnatural state of the city might perhaps require, that of distributing vast quantities of corn to the poorer citizens gratuitously. Two hundred thousand received this distribution in Augustus’s time; and it is highly probable that a great part of them had little else to depend upon. It is supposed to have been given to every man of full years; but the quantity was not enough for a family, and too much for an individual.
*16 It could not therefore enable them to increase; and, from the manner in which Plutarch speaks of the custom of exposing children among the poor,
*17 there is great reason to believe that many were destroyed in spite of the
jus trium liberorum. The passage in Tacitus, in which, speaking of the Germans, he alludes to this custom in Rome, seems to point to the same conclusion.
*18 What effect, indeed, could such a law have among a set of people, who appear to have been so completely excluded from all the means of acquiring a subsistence, except that of charity, that they would be scarcely able to support themselves, much less a wife and two or three children? If half of the slaves had been sent out of the country, and the people had been employed in agriculture and manufactures, the effect would have been to increase the number of Roman citizens with more certainty and rapidity than ten thousand laws for the encouragement of children.

It is possible that the
jus trium liberorum, and the other laws of the same tendency, might have been of some little use among the higher classes of Roman citizens; and indeed from the nature of these laws, consisting as they did principally of privileges, it would appear that they were directed chiefly to this part of society. But vicious habits of every possible kind preventive of population
*19 seem to have been so generally prevalent at this period, that no corrective laws could have any considerable influence. Montesquieu justly observes, that “the corruption of manners had destroyed the office of censor, which had been established itself to destroy the corruption of manners; but when the corruption of manners becomes general, censure has no longer any force.”
*20 Thirty-four years after the passing of the law of Augustus respecting marriage, the Roman knights demanded its repeal. On separating the married and the unmarried, it appeared that the latter considerably exceeded in number the former; a strong proof of the inefficacy of the law.
*21

In most countries vicious habits preventive of population appear to be a consequence, rather than a cause, of the infrequency of marriage; but in Rome the depravity of morals seems to have been the direct cause which checked the marriage union, at least among the higher classes. It is impossible to read the speech of Metellus Numidicus in his censorship without indignation and disgust. “If it were possible,” he says, “entirely to go without wives, we would deliver ourselves at once from this evil; but as the laws of nature have so ordered it that we can neither live happy with them nor continue the species with out them, we ought to have more regard for our lasting security than for our transient pleasures.”
*22

Positive laws to encourage marriage and population, enacted on the urgency of the occasion, and not mixed with religion, as in China and some other countries, are seldom calculated to answer the end which they aim at, and therefore generally indicate ignorance in the legislator who proposes them; but the apparent necessity of such laws almost invariably indicates a very great degree of moral and political depravity in the state; and in the countries in which they are most strongly insisted on, not only vicious manners will generally be found to prevail, but political institutions extremely unfavourable to industry, and consequently to population.

On this account I cannot but agree with Wallace
*23 in thinking that Hume was wrong in his supposition, that the Roman world was probably the most populous during the long peace under Trajan and the Antonines.
*24 We well know that wars do not depopulate much while industry continues in vigour; and that peace will not increase the number of people when they cannot find the means of subsistence. The renewal of the laws relating to marriage under Trajan, indicates the continued prevalence of vicious habits and of a languishing industry, and seems to be inconsistent with the supposition of a great increase of population.

It might be said perhaps that the vast profusion of slaves would more than make up for the want of Roman citizens; but it appears that the labour of these slaves was not sufficiently directed to agriculture to support a very great population. Whatever might be the case with some of the provinces, the decay of agriculture in Italy seems to be generally acknowledged. The pernicious custom of importing great quantities of corn to distribute gratuitously among the people had given it a blow, which it never afterwards recovered. Hume observes that “when the Roman authors complain that Italy, which formerly exported corn, became dependent on all the provinces for its daily bread, they never ascribed this alteration to the increase of its inhabitants, but to the neglect of tillage and agriculture.”
*25 And in another place he says, “All ancient authors tell us that there was a perpetual influx of slaves to Italy from the remoter provinces, particularly Syria, Cilicia, Cappadocia, and the lesser Asia, Thrace, and Egypt; yet the number of people did not increase in Italy; and writers complain of the continual decay of industry and agriculture.”
*26 It seems but little probable that the peace under Trajan and the Antonines should have given so sudden a turn to the habits of the people as essentially to alter this state of things.

On the condition of slavery it may be observed that there cannot be a stronger proof of its unfavourableness to the propagation of the species in the countries where it prevails, than the necessity of this continual influx. This necessity forms at once a complete refutation of the observation of Wallace, that the ancient slaves were more serviceable in raising up people than the inferior ranks of men in modern times.
*27 Though it is undoubtedly true, as he observes, that all our labourers do not marry, and that many of their children die, or become sickly and useless through the poverty and negligence of their parents;
*28 yet, notwithstanding these obstacles to increase, there is perhaps scarcely an instance to be produced where the lower classes of society in any country, if free, do not raise up people fully equal to the demand for their labour.

To account for the checks to population which are peculiar to a state of slavery, and which render a constant recruit of numbers necessary, we must adopt the comparison of slaves to cattle which Wallace and Hume have made; Wallace, to shew that it would be the interest of masters to take care of their slaves and rear up their offspring;
*29 and Hume, to prove that it would more frequently be the interest of the master to prevent than to encourage their breeding.
*30 If Wallace’s observation had been just, it is not to be doubted that the slaves would have kept up their own numbers with ease by procreation; and as it is acknowledged that they did not do this, the truth of Hume’s observation is clearly evinced. “To rear a child in London till he could be serviceable, would cost much dearer than to buy one of the same age from Scotland or Ireland, where he had been raised in a cottage, covered with rags, and fed on oatmeal and potatoes. Those who had slaves therefore, in all the richer and more populous countries, would discourage the pregnancy of the females, and either prevent or destroy the birth.”
*31 It is acknowledged by Wallace that the male slaves greatly exceeded in number the females,
*32 which must necessarily be an additional obstacle to their increase. It would appear therefore that the preventive check to population must have operated with very great force among the Greek and Roman slaves; and as they were often ill treated, fed perhaps scantily, and sometimes great numbers of them confined together in close and unwholesome
ergastula, or dungeons,
*33 it is probable that the positive checks to population from disease were also severe, and that when epidemics prevailed, they would be most destructive in this part of the society.

The unfavourableness of slavery to the propagation of the species in the country where it prevails, is not however decisive of the question respecting the absolute population of such a country, or the greater question respecting the populousness of ancient and modern nations. We know that some countries could afford a great and constant supply of slaves without being in the smallest degree depopulated themselves; and if these supplies were poured in, as they probably would be, exactly in proportion to the demand for labour in the nation which received them, the question respecting the populousness of this nation would rest precisely on the same grounds as in modern states, and depend upon the number of people which it could employ and support. Whether the practice of domestic slavery therefore prevail or not, it may be laid down as a position not to be controverted, that, taking a sufficient extent of territory to include within it exportation and importation, and allowing some variation for the prevalence of luxury or of frugal habits, the population of these countries will always be in proportion to the food which the earth is made to produce. And no cause, physical or moral, unless, it operate in an excessive and unusual manner,
*34 will have any considerable and permanent effect on the population, except in as far as it influences the production and distribution of the means of subsistence.

In the controversy concerning the populousness of ancient and modern nations this point has not been sufficiently attended to; and physical and moral causes have been brought forward on both sides, from which no just inference in favour of either party could be drawn. It seems to have escaped the attention of both writers, that the more productive and populous a country is in its actual state, the less probably will be its power of obtaining a further increase of produce; and consequently the more checks must necessarily be called into action, to keep the population down to the level of this stationary or slowly increasing produce. From finding such checks, therefore, in ancient or modern nations, no inference can be drawn against the absolute populousness of either. On this account, the prevalence of the small-pox, and of other disorders unknown to the ancients, can by no means be considered as an argument against the populousness of modern nations, though to these physical causes both Hume
*35 and Wallace
*36 allow considerable weight.

In the moral causes which they have brought forward, they have fallen into a similar error. Wallace introduces the positive encouragements to marriage among the ancients as one of the principal causes of the superior populousness of the ancient world;
*37 but the necessity of positive laws to encourage marriage certainly rather indicates a want than an abundance of people; and in the instance of Sparta, to which he particularly refers, it appears from the passage in Aristotle, mentioned in the last chapter, that the laws to encourage marriage were instituted for the express purpose of remedying a marked deficiency of people. In a country with a crowded and overflowing population, a legislator would never think of making express laws to encourage marriage and the procreation of children. Other arguments of Wallace will be found upon examination to be almost equally ineffectual to his purpose.

Some of the causes which Hume produces are in the same manner unsatisfactory, and rather make against the inference which he has in view than for it. The number of footmen, housemaids and other persons remaining unmarried in modern states, he allows to be an argument against their populousness.
*38 But the contrary inference of the two appears to be the more probable. When the difficulties attending the rearing a family are very great, and consequently many persons of both sexes remain single, we may naturally enough infer that population is stationary, but by no means that it is not absolutely great; because the difficulty of rearing a family may arise from the very circumstance of a great absolute population, and the consequent fulness of all the channels to a livelihood; though the same difficulty may undoubtedly exist in a thinly-peopled country, which is yet stationary in its population. The number of unmarried persons in proportion to the whole number, may form some criterion by which we can judge whether population be increasing, stationary, or decreasing; but will not enable us to determine any thing respecting absolute populousness. Yet even in this criterion we are liable to be deceived. In some of the southern countries early marriages are general, and very few women remain in a state of celibacy; yet the people not only do not increase, but the actual number is perhaps small. In this case the removal of the preventive check is made up by the excessive force of the positive check. The sum of all the positive and preventive checks taken together, forms undoubtedly the immediate cause which represses population; but we never can expect to obtain and estimate accurately this sum in any country; and we can certainly draw no safe conclusion from the contemplation of two or three of these checks taken by themselves, because it so frequently happens that the excess of one check is balanced by the defect of some other. Causes, which affect the number of births or deaths, may or may not affect the average population, according to circumstances; but causes, which affect the production and distribution of the means of subsistence, must necessarily affect population; and it is therefore upon these latter causes alone (independently of actual enumerations) that we can with certainty rely.

All the checks to population, which have been hitherto considered in the course of this review of human society, are clearly resolvable into moral restraint, vice, and misery.

Of that branch of the preventive check which I have denominated moral restraint, though it has certainly had some share in repressing the natural power of population, yet, taken in its strict sense, it must be allowed to have operated feebly, compared with the others. Of the other branch of the preventive check, which comes under the head of vice, though its effect appears to have been very considerable in the later periods of Roman history, and in some other countries; yet, upon the whole, its operation seems to have been inferior to the positive checks. A large portion of the procreative power appears to have been called into action, the redundancy from which was checked by violent causes. Among these, war is the most prominent and striking feature; and after this may be ranked famines and violent diseases. In most of the countries considered, the population seems to have been seldom measured accurately according to the average and permanent means of subsistence, but generally to have vibrated between the two extremes; and consequently the oscillations between want and plenty are strongly marked, as we should naturally expect among less civilized nations.