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Chapter VII. A probable cause of epidemics - Thomas Robert Malthus, An Essay on the Principle of Population [1798, 1st ed.] 
An Essay on the Principle of Population, as it affects the future Improvement of Society, with Remarks on the Speculations of Mr. Godwin, M. Condorcet, and Other Writers (London: J. Johnson 1798). 1st edition.
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A probable cause of epidemics—Extracts from Mr. Sussmilch's tables—Periodical returns of sickly seasons to be expected in certain cases—Proportion of births to burials for short periods in any country an inadequate criterion of the real average increase of population—Best criterion of a permanent increase of population—Great frugality of living one of the causes of the famines of China and Indostan—Evil tendency of one of the clauses in Mr. Pitt's Poor Bill—Only one proper way of encouraging population—Causes of the happiness of nations—Famine, the last and most dreadful mode by which nature represses a redundant population—The three propositions considered as established.
By great attention to cleanliness, the plague seems at length to be completely expelled from London. But it is not improbable, that among the secondary causes that produce even sickly seasons and epidemics, ought to be ranked a crowded population and unwholesome and insufficient food. I have been led to this remark, by looking over some of the tables of Mr. Sussmilch, which Dr. Price has extracted in one of his notes to the postscript on the controversy respecting the population of England and Wales. They are considered as very correct; and if such tables were general, they would throw great light on the different ways by which population is repressed, and prevented from increasing beyond the means of subsistence in any country. I will extract a part of the tables, with Dr. Price's remarks.
"N.B. In 1709 and 1710, a pestilence carried off 247,733 of the inhabitants of this country, and in 1736 and 1737, epidemics prevailed, which again checked its increase."
It may be remarked, that the greatest proportion of births to burials, was in the five years after the great pestilence.
"In this instance the inhabitants appear to have been almost doubled in 56 years, no very bad epidemics having once interrupted the increase, but the three years immediately following the last period (to 1759,) were so sickly that the births were sunk to 10,229 and the burials raised to 15,068."
Is it not probable, that in this case, the number of inhabitants had increased faster than the food and the accommodations necessary to preserve them in health? The mass of the people would, upon this supposition, be obliged to live harder, and a greater number would be crowded together in one house; and it is not surely improbable that these were among the natural causes that produced the three sickly years. These causes may produce such an effect, though the country, absolutely considered, may not be extremely crowded and populous. In a country even thinly inhabited, if an increase of population take place, before more food is raised, and more houses are built, the inhabitants must be distressed in some degree for room and subsistence. Were the marriages in England, for the next eight or ten years, to be more prolifick than usual, or even were a greater number of marriages than usual to take place, supposing the number of houses to remain the same; instead of five or six to a cottage, there must be seven or eight; and this, added to the necessity of harder living, would probably have a very unfavourable effect on the health of the common people.
"Epidemics prevailed for six years, from 1736, to 1741, which checked the increase."
"The years 1738, 1740, 1750, and 1751, were particularly sickly."
For further information on this subject, I refer the reader to Mr. Sussmilch's tables. The extracts that I have made are sufficient to shew the periodical, though irregular, returns of sickly seasons, and it seems highly probable, that a scantiness of room and food was one of the principal causes that occasioned them.
It appears from the tables, that these countries were increasing rather fast for old states, notwithstanding the occasional seasons that prevailed. Cultivation must have been improving, and marriages, consequently, encouraged. For the checks to population appear to have been rather of the positive, than of the preventive kind. When from a prospect of increasing plenty in any country, the weight that represses population is in some degree removed; it is highly probable that the motion will be continued beyond the operation of the cause that first impelled it. Or, to be more particular, when the increasing produce of a country, and the increasing demand for labour, so far ameliorate the condition of the labourer, as greatly to encourage marriage, it is probable that the custom of early marriages will continue, till the population of the country has gone beyond the increased produce: and sickly seasons appear to be the natural and necessary consequence. I should expect, therefore, that those countries where subsistence was increasing sufficiency at times to encourage population, but not to answer all its demands, would be more subject to periodical epidemics than those where the population could more completely accommodate itself to the average produce.
An observation the converse of this will probably also be found true. In those countries that are subject to periodical sicknesses, the increase of population, or the excess of births above the burials, will be greater in the intervals of these periods, than is usual, cæteris paribus, in the countries not so much subject to such disorders. If Turkey and Egypt have been nearly stationary in their average population for the last century, in the intervals of their periodical plagues, the births must have exceeded the burials in a greater proportion than in such countries as France and England.
The average proportion of births to burials in any country for a period of five to ten years, will hence appear to be a very inadequate criterion by which to judge of its real progress in population. This proportion certainly shews the rate of increase during those five or ten years; but we can by no means thence infer, what had been the increase for the twenty years before, or what would be the increase for the twenty years after. Dr. Price observes, that Sweden, Norway, Russia, and the kingdom of Naples, are increasing fast; but the extracts from registers that he has given are not for periods of sufficient extent to establish the fact. It is highly probable, however, that Sweden, Norway, and Russia, are really increasing their population, though not at the rate that the proportion of births to burials for the short periods that Dr. Price takes would seem to shew.4 For five years, ending in 1777, the proportion of births to burials in the kingdom of Naples was 144 to 100; but there is reason to suppose that this proportion would indicate an increase much greater than would be really found to have taken place in that kingdom during a period of a hundred years.
Dr. Short compared the registers of many villages and market towns in England for two periods; the first, from Queen Elizabeth to the middle of the last century, and the second, from different years at the end of the last century, to the middle of the present. And from a comparison of these extracts, it appears that in the former period the births exceeded the burials in the proportion of 124 to 100; but in the latter, only in the proportion of 111 to 100. Dr. Price thinks that the registers in the former period are not to be depended upon; but, probably, in this instance, they do not give incorrect proportions. At least, there are many reasons for expecting to find a greater excess of births above the burials in the former period than in the latter. In the natural progress of the population of any country, more good land will, cæteris paribus,5 be taken into cultivation in the earlier stages of it than in the later. And a greater proportional yearly increase of produce will almost invariably be followed by a greater proportional increase of population. But, besides this great cause, which would naturally give the excess of births above burials greater at the end of Queen Elizabeth's reign, than in the middle of the present century, I cannot help thinking that the occasional ravages of the plague in the former period, must have had some tendency to increase this proportion. If an average of ten years had been taken in the intervals of the returns of this dreadful disorder; or if the years of plague had been rejected as accidental, the registers would certainly give the proportion of births to burials too high for the real average increase of the population. For some few years after the great plague in 1666, it is probable that there was a more than usual excess of births above burials, particularly if Dr. Price's opinion be founded, that England was more populous at the revolution (which happened only 22 years afterwards) than it is at present.
Mr. King, in 1693, stated the proportion of the births to the burials throughout the Kingdom, exclusive of London, as 115 to 100. Dr. Short makes it, in the middle of the present century, 111 to 100, including London. The proportion in France for five years, ending in 1774, was 117 to 100. If these statements are near the truth; and if there are no very great variations at particular periods in the proportions, it would appear that the population of France and England has accommodated itself very nearly to the average produce of each country. The discouragements to marriage, the consequent vicious habits, war, luxury, the silent though certain depopulation of large towns, and the close habitations, and insufficient food of many of the poor, prevent population from increasing beyond the means of subsistence; and, if I may use an expression which certainly at first appears strange, supercede the necessity of great and ravaging epidemics to repress what is redundant. Were a wasting plague to sweep off two millions in England, and six millions in France, there can be no doubt whatever that, after the inhabitants had recovered from the dreadful shock, the proportion of births to burials would be much above what it is in either country at present.
In New Jersey, the proportion of births to deaths on an average of seven years, ending in 1743, was as 300 to 100. In France and England, taking the highest proportion, it is as 117 to 100. Great and astonishing as this difference is, we ought not to be so wonder-struck at it, as to attribute it to the miraculous interposition of heaven. The causes of it are not remote, latent and mysterious; but near us, round about us, and open to the investigation of every inquiring mind. It accords with the most liberal spirit of philosophy, to suppose that not a stone can fall, or a plant rise, without the immediate agency of divine power. But we know from experience, that these operations of what we call nature have been conducted almost invariably according to fixed laws. And since the world began, the causes of population and depopulation have probably been as constant as any of the laws of nature with which we are acquainted.
The passion between the sexes has appeared in every age to be so nearly the same that it may always be considered, in algebraic language, as a given quantity. The great law of necessity which prevents population from increasing in any country beyond the food which it can either produce or acquire, is a law, so open to our view, so obvious and evident to our understandings, and so completely confirmed by the experience of every age, that we cannot for a moment doubt it. The different modes which nature takes to prevent or repress a redundant population, do not appear, indeed, to us so certain and regular; but though we cannot always predict the mode, we may with certainty predict the fact. If the proportion of births to deaths for a few years, indicate an increase of numbers much beyond the proportional increased or acquired produce of the country, we may be perfectly certain, that unless an emigration takes place, the deaths will shortly exceed the births; and that the increase that had taken place for a few years cannot be the real average increase of the population of the country. Were there no other depopulating causes, every country would, without doubt, be subject to periodical pestilences or famine.
The only true criterion of a real and permanent increase in the population of any country, is the increase of the means of subsistence. But even this criterion is subject to some slight variations which are, however, completely open to our view and observations. In some countries population appears to have been forced; that is, the people have been habituated by degrees to live almost upon the smallest possible quantity of food. There must have been periods in such counties when population increased permanently, without an increase in the means of subsistence. China seems to answer to this description. If the accounts we have of it are to be trusted, the lower classes of people are in the habit of living almost upon the smallest possible quantity of food, and are glad to get any putrid offals that European labourers would rather starve than eat. The law in China which permits parents to expose their children, has tended principally thus to force the population. A nation in this state must necessarily be subject to famines. Where a country is so populous in proportion to the means of subsistence, that the average produce of it is but barely sufficient to support the lives of the inhabitants, any deficiency from the badness of seasons must be fatal. It is probable that the very frugal manner in which the Gentoos are in the habit of living, contributes in some degree to the famines of Indostan.
In America, where the reward of labour is at present so liberal, the lower classes might retrench very considerably in a year of scarcity without materially distressing themselves. A famine therefore seems to be almost impossible. It may be expected, that in the progress of the population of America, the labourers will in time be much less liberally rewarded. The numbers will in this case permanently increase without a proportional increase in the means of subsistence.
In the different States of Europe there must be some variations in the proportion between the number of inhabitants and the quantity of food consumed, arising from the different habits of living that prevail in each State. The labourers of the South of England are so accustomed to eat fine wheaten bread, that they will suffer themselves to be half starved before they will submit to live like the Scotch peasants. They might perhaps in time, by the constant operation of the hard law of necessity, be reduced to live even like the lower Chinese: and the country would then, with the same quantity of food, support a greater population. But to effect this must always be a most difficult, and every friend to humanity will hope, an abortive attempt. Nothing is so common as to hear of encouragements that ought to be given to population. If the tendency of mankind to increase be so great as I have represented it to be, it may appear strange that this increase does not come when it is thus repeatedly called for. The true reason is, that the demand for a greater population is made without preparing the funds necessary to support it. Increase the demand for agricultural labour by promoting cultivation, and with it consequently increase the produce of the country, and ameliorate the condition of the labourer, and no apprehensions whatever need be entertained of the proportional increase of population. An attempt to effect this purpose in any other way is vicious, cruel, and tyrannical, and in any state of tolerable freedom cannot therefore succeed. It may appear to be the interest of the rulers, and the rich of a State, to force population, and thereby lower the price of labour, and consequently the expense of fleets and armies, and the cost of manufactures for foreign sale: but every attempt of the kind should be carefully watched and strenuously resisted by the friends of the poor, particularly when it comes under the deceitful garb of benevolence, and is likely, on that account, to be cheerfully and cordially received by the common people.
I entirely acquit Mr. Pitt of any sinister intention in that clause of his poor bill which allows a shilling a week to every labourer for each child he has above three. I confess, that before the bill was brought into Parliament, and for some time after, I thought that such a regulation would be highly beneficial; but further reflection on the subject has convinced me, that if its object be to better the condition of the poor, it is calculated to defeat the very purpose which it has in view. It has no tendency that I can discover to increase the produce of the country; and if it tend to increase the population, without increasing the produce, the necessary and inevitable consequence appears to be that the same produce must be divided among a greater number, and consequently that a day's labour will purchase a smaller quantity of provisions, and the poor therefore in general must be more distressed.
I have mentioned some cases where population may permanently Increase, without a proportional increase in the means of subsistence. But it is evident that the variation in different States, between the food and the numbers supported by it, is restricted to a limit beyond which it cannot pass. In every country, the population of which is not absolutely decreasing, the food must be necessarily sufficient to support, and to continue, the race of labourers.
Other circumstances being the same, it may be affirmed that countries are populous, according to the quantity of human food which they produce; and happy, according to the liberality with which that food is divided, or the quantity which a day's labour will purchase. Corn countries are more populous than pasture countries; and rice countries more populous than corn countries. The lands in England are not suited to rice, but they would all bear potatoes: and Dr. Adam Smith observes, that if potatoes were to become the favourite vegetable food of the common people, and if the same quantity of land was employed in their culture, as is now employed in the culture of corn, the country would be able to support a much greater population; and would consequently in a very short time have it.
The happiness of a country does not depend, absolutely, upon its poverty, or its riches, upon its youth, or its age, upon its being thinly, or fully inhabited, but upon the rapidity with which it is increasing, upon the degree in which the yearly increase of food approaches to the yearly increase of an unrestricted population. This approximation is always the nearest in new colonies, where the knowledge and industry of an old State operate on the fertile unappropriated land of a new one. In other cases, the youth or the age of a State is not in this respect of very great importance. It is probable that the food of Great Britain is divided in as great plenty to the inhabitants, at the present period, as it was two thousand, three thousand, or four thousand years ago. And there is reason to believe that the poor and thinly inhabited tracts of the Scotch Highlands, are as much distressed by an overcharged population as the rich and populous province of Flanders.
Were a country never to be over-run by a people more advanced in arts, but left to its own natural progress in civilization; from the time that its produce might be considered as an unit, to the time that it might be considered as a million, during the lapse of many hundred years, there would not be a single period, when the mass of the people could be said to be free from distress, either directly or indirectly, for want of food. In every State in Europe, since we have first had accounts of it, millions and millions of human existences have been repressed from this simple cause; though perhaps in some of these States, an absolute famine has never been known.
Famine seems to be the last, the most dreadful resource of nature. The power of population is so superior to the power in the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction; and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague, advance in terrific array, and sweep off their thousands and ten thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.
Must it not then be acknowledged by an attentive examiner of the histories of mankind, that in every age and in every State in which man has existed, or does now exist,
[4.]See Dr. Price's Observations, 2 Vol. Postscript to the controversy on the population of England and Wales.
[5.]I say cæteris paribus, because the increase of the produce of any country will always very greatly depend on the spirit of industry that prevails, and the way in which it is directed. The knowledge and habits of the people, and other temporary causes, particularly the degree of civil liberty and equality existing at the time, must always have great influence in exciting and directing this spirit.