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CHAPTER XII: of the law of the increase of production from land - John Stuart Mill, Principles of Political Economy with some of their Applications to Social Philosophy (Ashley ed.) 
Principles of Political Economy with some of their Applications to Social Philosophy, ed. William James Ashley (London: Longmans, Green and Co., 1909, 7th ed.).
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of the law of the increase of production from land
§ 1. Land differs from the other elements of production, labour and capital, in not being susceptible of indefinite increase. Its extent is limited, and the extent of the more productive kinds of it more limited still. It is also evident that the quantity of produce capable of being raised on any given piece of land is not indefinite. This limited quantity of land, and limited productiveness of it, are the real limits to the increase of production.
That they are the ultimate limits, must always have been clearly seen. But since the final barrier has never in any instance been reached; since there is no country in which all the land, capable of yielding food, is so highly cultivated that a larger produce could not (even without supposing any fresh advance in agricultural knowledge) be obtained from it, and since a large portion of the earth's surface still remains entirely uncultivated; it is commonly thought, and is very natural at first to suppose, that for the present all limitation of production or population from this source is at an indefinite distance, and that ages must elapse before any practical necessity arises for taking the limiting principle into serious consideration.
I apprehend this to be not only an error, but the most serious one, to be found in the whole field of political economy. The question is more important and fundamental than any other; it involves the whole subject of the causes of poverty, in a rich and industrious community: and unless this one matter be thoroughly understood, it is to no purpose proceeding any further in our inquiry.
§ 2. The limitation to production from the properties of the soil, is not like the obstacle opposed by a wall, which stands immovable in one particular spot, and offers no hindrance to motion short of stopping it entirely. We may rather compare it to a highly elastic and extensible band, which is hardly ever so violently stretched that it could not possibly be stretched any more, yet the pressure of which is felt long before the final limit is reached, and felt more severely the nearer that limit is approached.
After a certain, and not very advanced, stage in the progress of agriculture,1 it is the law of production from the land, that in any given state of agricultural skill and knowledge, by increasing the labour, the produce is not increased in an equal degree; doubling the labour does not double the produce; or, to express the same thing in other words, every increase of produce is obtained by a more than proportional increase in the application of labour to the land.
This general law of agricultural industry is the most important proposition in political economy. Were the law different, nearly all the phenomena of the production and distribution of wealth would be other than they are. The most fundamental errors which still prevail on our subject, result from not perceiving this law at work underneath the more superficial agencies on which attention fixes itself; but mistaking those agencies for the ultimate causes of effects of which they may influence the form and mode, but of which it alone determines the essence.
When, for the purpose of raising an increase of produce, recourse is had to inferior land, it is evident that, so far, the produce does not increase in the same proportion with the labour. The very meaning of inferior land, is land which with equal labour returns a smaller amount of produce. Land may be inferior either in fertility or in situation. The one requires a greater proportional amount of labour for growing the produce, the other for carrying it to market. If the land A yields a thousand quarters of wheat, to a given outlay in wages, manure, &c., and in order to raise another thousand recourse must be had to the land B, which is either less fertile or more distant from the market, the two thousand quarters will cost more than twice as much labour as the original thousand, and the produce of agriculture will be increased in a less ratio than the labour employed in procuring it.
Instead of cultivating the land B, it would be possible, by higher cultivation, to make the land A produce more. It might be ploughed or harrowed twice instead of once, or three times instead of twice; it might be dug instead of being ploughed; after ploughing, it might be gone over with a hoe instead of a harrow, and the soil more completely pulverized; it might be oftener or more thoroughly weeded; the implements used might be of higher finish, or more elaborate construction; a greater quantity or more expensive kinds of manure might be applied, or when applied, they might be more carefully mixed and incorporated with the soil. These are some of the modes by which the same land may be made to yield a greater produce; and when a greater produce must be had, some of these are among the means usually employed for obtaining it. But, that it is obtained at a more than proportional increase of expense, is evident from the fact that inferior lands are cultivated. Inferior lands, or lands at a greater distance from the market, of course yield an inferior return, and an increasing demand cannot be supplied from them unless at an augmentation of cost, and therefore of price. If the additional demand could continue to be supplied from the superior lands, by applying additional labour and capital, at no greater proportional cost than that at which they yield the quantity first demanded of them, the owners or farmers of those lands could undersell all others, and engross the whole market. Lands of a lower degree of fertility or in a more remote situation, might indeed be cultivated by their proprietors, for the sake of subsistence or independence; but it never could be the interest of any one to farm them for profit. That a profit can be made from them, sufficient to attract capital to such an investment, is a proof that cultivation on the more eligible lands has reached a point, beyond which any greater application of labour and capital would yield, at the best, no greater return than can be obtained at the same expense from less fertile or less favourably situated lands.
The careful cultivation of a well-farmed district of England or Scotland is a symptom and an effect of the more unfavourable terms which the land has begun to exact for any increase of its fruits. Such elaborate cultivation costs much more in proportion, and requires a higher price to render it profitable, than farming on a more superficial system; and would not be adopted if access could be had to land of equal fertility, previously unoccupied. Where there is the choice of raising the increasing supply which society requires, from fresh land of as good quality as that already cultivated, no attempt is made to extract from land anything approaching to what it will yield on what are esteemed the best European modes of cultivating. The land is tasked up to the point at which the greatest return is obtained in proportion to the labour employed, but no further: any additional labour is carried elsewhere. “It is long,” says an intelligent traveller in the United States,∗ “before an English eye becomes reconciled to the lightness of the crops and the careless farming (as we should call it) which is apparent. One forgets that where land is so plentiful and labour so dear as it is here, a totally different principle must be pursued to that which prevails in populous countries, and that the consequence will of course be a want of tidiness, as it were, and finish, about everything which requires labour.” Of the two causes mentioned, the plentifulness of land seems to me the true explanation, rather than the dearness of labour; for, however dear labour may be, when food is wanted, labour will always be applied to producing it in preference to anything else. But this labour is more effective for its end by being applied to fresh soil, than if it were employed in bringing the soil already occupied into higher cultivation. Only when no soils remain to be broken up but such as either from distance or inferior quality require a considerable rise of price to render their cultivation profitable, can it become advantageous to apply the high farming of Europe to any American lands; except, perhaps, in the immediate vicinity of towns, where saving in cost of carriage may compensate for great inferiority in the return from the soil itself. As American farming is  to English, so is the ordinary English to that of Flanders, Tuscany, or the Terra di Lavoro; where by the application of a far greater quantity of labour there is obtained a considerably larger gross produce, but on such terms as would never be advantageous to a mere speculator for profit, unless made so by much higher prices of agricultural produce.
The principle which has now been stated must be received, no doubt, with certain explanations and limitations. Even after the land is so highly cultivated that the mere application of additional labour, or of an additional amount of ordinary dressing, would yield no return proportioned to the expense, it may still happen that the application of a much greater additional labour and capital to improving the soil itself, by draining or permanent manures, would be as liberally remunerated by the produce, as any portion of the labour and capital already employed. It would sometimes be much more amply remunerated. This could not be, if capital always sought and found the most advantageous employment; but if the most advantageous employment has to wait longest for its remuneration, it is only in a rather advanced stage of industrial development that the preference will be given to it; and even in that advanced stage, the laws or usages connected with property in land and the tenure of farms, are often such as to prevent the disposable capital of the country from flowing freely into the channel of agricultural improvement: and hence the increased supply, required by increasing population, is sometimes raised at an augmenting cost by higher cultivation, when the means of producing it without increase of cost are known and accessible. There can be no doubt, that if capital were forthcoming to execute, within the next year, all known and recognised improvements in the land of the United Kingdom which would pay at the existing prices, that is, which would increase the produce in as great or a greater ratio than the expense; the result would be such (especially if we include Ireland in the supposition) that inferior land would not for a long time require to be brought under tillage: probably a considerable part of the less productive lands now cultivated, which are not particularly favoured by situation, would go out of culture; or (as the improvements in question are not so much applicable to good land, but operate rather by converting bad land into good) the contraction of cultivation might principally take place by a less high dressing and less elaborate tilling of land generally; a falling back to something nearer the character of American farming; such only of the poor lands being altogether abandoned as were not found susceptible of improvement. And thus the aggregate produce of the whole cultivated land would bear a larger proportion than before to the labour expended on it; and the general law of diminishing return from land would have undergone, to that extent, a temporary supersession. No one, however, can suppose that even in these circumstances, the whole produce required for the country could be raised exclusively from the best lands, together with those possessing advantages of situation to place them on a par with the best. Much would undoubtedly continue to be produced under less advantageous conditions, and with a smaller proportional return, than that obtained from the best soils and situations. And in proportion as the further increase of population required a still greater addition to the supply, the general law would resume its course, and the further augmentation would be obtained at a more than proportionate expense of labour and capital.
3. 1 That the produce of land increases, caeteris paribus, in a diminishing ratio to the increase in the labour employed, is a truth more often ignored or disregarded than actually denied. It has, however, met with a direct impugner in the well-known American political economist, Mr. H. C. Carey, who maintains that the real law of agricultural industry is the very reverse; the produce increasing in a greater ratio than the labour, or in other words affording to labour a perpetually increasing return. To substantiate this assertion, he argues that cultivation does not begin with the better soils, and extend from them, as the demand increases, to the poorer, but begins with the poorer, and does not, till long after, extend itself to the more fertile. Settlers in a new country invariably commence on the high and thin lands; the rich but swampy soils of the river bottoms cannot at first be brought into cultivation, by reason of their unhealthiness, and of the great and prolonged labour required for clearing and draining them. As population and wealth increase, cultivation travels down the hill sides, clearing them as it goes, and the most fertile soils, those of the low grounds, are generally (he even says universally) the latest cultivated. These propositions, with the inferences which Mr. Carey draws from them, are set forth at much length in his latest and most elaborate treatise, Principles of Social Science; and he considers them as subverting the very foundation of what he calls the English political economy, with all its practical consequences, especially the doctrine of free trade.
As far as words go, Mr. Carey has a good case against several of the highest authorities in political economy, who certainly did enunciate in too universal a manner the law which they laid down, not remarking that it is not true of the first cultivation in a newly settled country. Where population is thin and capital scanty, land which requires a large outlay to render it fit for tillage must remain untilled; though such lands, when their time has come, often yield a greater produce than those earlier cultivated, not only absolutely, but proportionally to the labour employed, even if we include that which had been expended in originally fitting them for culture. But it is not pretended that the law of diminishing return was operative from the very beginning of society: and though some political economists may have believed it to come into operation earlier than it does, it begins quite early enough to support the conclusions they founded on it. Mr. Carey will hardly assert that in any old country—in England or France, for example—the lands left waste are, or have for centuries been, more naturally fertile than those under tillage. Judging even by his own imperfect test, that of local situation—how imperfect I need not stop to point out—is it true that in England or France at the present day the uncultivated part of the soil consists of the plains and valleys, and the cultivated, of the hills? Every one knows, on the contrary, that it is the high lands and thin soils which are left to nature, and when the progress of population demands an increase of cultivation, the extension is from the plains to the hills. Once in a century, perhaps, a Bedford Level may be drained, or a Lake of Harlem pumped out: but these are slight and transient exceptions to the normal progress of things; and in old countries which are at all advanced in civilization, little of this sort remains to be done.∗
Mr. Carey himself unconsciously bears the strongest testimony to the reality of the law he contends against: for one of the propositions most strenuously maintained by him is, that the raw products of the soil, in an advancing community, steadily tend to rise in price. Now, the most elementary truths of political economy show that this could not happen, unless the cost of production, measured in labour, of those products, tended to rise. If the application of additional labour to the land was, as a general rule, attended with an increase in the proportional return, the price of produce, instead of rising, must necessarily fall as society advances, unless the cost of production of gold and silver fell still more: a case so rare, that there are only two periods in all history when it is known to have taken place; the one, that which followed the opening of the Mexican and Peruvian mines; the other, that in which we now live. At all known periods, except these two, the cost of production of the precious metals has been either stationary or rising. If, therefore, it be true that the tendency of agricultural produce is to rise in money price as wealth and population increase, there needs no other evidence that the labour required for raising it from the soil tends to augment when a greater quantity is demanded.
I do not go so far as Mr. Carey: I do not assert that the cost of production, and consequently the price, of agricultural produce, always and necessarily rises as population increases. It tends to do so; but the tendency may be, and sometimes is, even during long periods, held in check. The effect does not depend on a single principle, but on two antagonizing principles. There is another agency, in habitual antagonism to the law of diminishing return from land; and to the consideration of this we shall now proceed. It is no other than the progress of civilization. I use this general and somewhat vague expression, because the things to be included are so various, that hardly any term of a more restricted signification would comprehend them all.
Of these, the most obvious is the progress of agricultural knowledge, skill, and invention. Improved processes of agriculture are of two kinds: some enable the land to yield a greater absolute produce, without an equivalent increase of labour; others have not the power of increasing the produce, but have that of diminishing the labour and expense by which it is obtained. Among the first are to be reckoned the disuse of fallows, by means of the rotation of crops; and the introduction of new articles of cultivation capable of entering advantageously into the rotation. The change made in British agriculture towards the close of the last century, by the introduction of turnip husbandry, is spoken of as amounting to a revolution. These improvements operate not only by enabling the land to produce a crop every year, instead of remaining idle one year in every two or three to renovate its powers, but also by direct increase of its productiveness; since the great addition made to the number of cattle by the increase of their food, affords more abundant manure to fertilize the corn lands. Next in order comes the introduction of new articles of food, containing a greater amount of sustenance, like the potato, or more productive species or varieties of the same plant, such as the Swedish turnip. In the same class of improvements must be placed a better knowledge of the properties of manures, and of the most effectual modes of applying them; the introduction of new and more powerful fertilizing agents, such as guano, and the conversion to the same purpose, of substances previously wasted; inventions like subsoil-ploughing or tile draining; improvements in the breed or feeding of labouring cattle; augmented stock of the animals which consume and convert into human food what would otherwise be wasted; and the like. The other sorts of improvements, those which diminish labour, but without increasing the capacity of the land to produce, are such as the improved construction of tools; the introduction of new instruments which spare manual labour, as the winnowing and threshing machines; a more skilful and economical application of muscular exertion, such as the introduction, so slowly accomplished in England, of Scotch ploughing, with two horses abreast and one man, instead of three or four horses in a team and two men, &c. These improvements do not add to the productiveness of the land, but they are equally calculated with the former to counteract the tendency in the cost of production of agricultural produce to rise with the progress of population and demand.
Analogous in effect to this second class of agricultural improvements, are improved means of communication. Good roads are equivalent to good tools. It is of no consequence whether the economy of labour takes place in extracting the produce from the soil, or in conveying it to the place where it is to be consumed. Not to say in addition, that the labour of cultivation itself is diminished by whatever lessens the cost of bringing manure from a distance, or facilitates the many operations of transport from place to place which occur within the bounds of the farm. Railways and canals are virtually a diminution of the cost of production of all things sent to market by them; and literally so of all those, the appliances and aids for producing which, they serve to transmit. By their means land can be cultivated, which could not otherwise have remunerated the cultivators without a rise of price. Improvements in navigation have, with respect to food or materials brought from beyond sea, a corresponding effect.
From similar considerations, it appears that many purely mechanical improvements, which have, apparently at least, no peculiar connexion with agriculture, nevertheless enable a given amount of food to be obtained with a smaller expenditure of labour. A great improvement in the process of smelting iron, would tend to cheapen agricultural implements, diminish the cost of railroads, of waggons and carts, ships, and perhaps buildings, and many other things to which iron is not at present applied, because it is too costly; and would thence diminish the cost of production of food. The same effect would follow from an improvement in those processes of what may be termed manufacture to which the material of food is subjected after it is separated from the ground. The first application of wind or water power to grind corn tended to cheapen bread as much as a very important discovery in agriculture would have done; and any great improvement in the construction of corn-mills, would have, in proportion, a similar influence. The effects of cheapening locomotion have been already considered. There are also engineering inventions which facilitate all great operations on the earth's surface. An improvement in the art of taking levels is of importance to draining, not to mention canal and railway making. The fens of Holland, and of some parts of England, are drained by pumps worked by the wind or by steam. Where canals of irrigation, or where tanks or embankments are necessary, mechanical skill is a great resource for cheapening production.
Those manufacturing improvements which cannot be made instrumental to facilitate, in any of its stages, the actual production of food, and therefore do not help to counteract or retard the diminution of the proportional return to labour from the soil, have, however, another effect, which is practically equivalent. What they do not prevent, they yet, in some degree, compensate for.
The materials of manufacture being all drawn from the land, and many of them from agriculture, which supplies in particular the entire material of clothing; the general law of production from the land, the law of diminishing return, must in the last resort be applicable to manufacturing as well as to agricultural history. As population increases, and the power of the land to yield increased produce is strained harder and harder, any additional supply of material, as well as of food, must be obtained by a more than proportionally increasing expenditure of labour. But the cost of the material forming generally a very small portion of the entire cost of the manufacture, the agricultural labour concerned in the production of manufactured goods is but a small fraction of the whole labour worked up in the commodity. All the rest of the labour tends constantly and strongly towards diminution, as the amount of production increases. Manufactures are vastly more susceptible than agriculture of mechanical improvements, and contrivances for saving labour; and it has already been seen how greatly the skilful and economical distribution, depend on the extent of the market, and on the possibility of production in large masses. In manufactures, accordingly, the causes tending to increase the productiveness of industry, preponderate greatly over the one cause which tends to diminish it: and the increase of production, called forth by the progress of society, takes place, not at an increasing, but at a continually diminishing proportional cost. This fact has manifested itself in the progressive fall of the prices and values of almost every kind of manufactured goods during two centuries past; a fall accelerated by the mechanical inventions of the last seventy or eighty years, and susceptible of being prolonged and extended beyond any limit which it would be safe to specify.
Now it is quite conceivable that the efficiency of agricultural labour might be undergoing, with the increase of produce, a gradual diminution; that the price of food, in consequence, might be progressively rising, and an ever growing proportion of the population might be needed to raise food for the whole; while yet the productive power of labour in all other branches of industry might be so rapidly augmenting, that the required amount of labour could be spared from manufactures, and nevertheless a greater produce be obtained, and the aggregate wants of the community be on the whole better supplied, than before. The benefit might even extend to the poorest class. The increased cheapness of clothing and lodging might make up to them for the augmented cost of their food.
There is, thus, no possible improvement in the arts of production which does not in one or another mode exercise an antagonist influence to the law of diminishing return to agricultural labour. Nor is it only industrial improvements which have this effect. Improvements in government, and almost every kind of moral and social advancement, operate in the same manner. Suppose a country in the condition of France before the Revolution: taxation imposed almost exclusively on the industrial classes, and on such a principle as to be an actual penalty on production; and no redress obtainable for any injury to property or person, when inflicted by people of rank, or court influence. Was not the hurricane which swept away this system of things, even if we look no further than to its effect in augmenting the productiveness of labour, equivalent to many industrial inventions? The removal of a fiscal burthen on agriculture, such as tithe, has the same effect as if the labour necessary for obtaining the existing produce were suddenly reduced one-tenth. The abolition of corn laws, or of any other restrictions which prevent commodities from being produced where the cost of their production is lowest, amounts to a vast improvement in production. When fertile land, previously reserved as hunting ground, or for any other purpose of amusement, is set free for culture, the aggregate productiveness of agricultural industry is increased. It is well known what has been the effect in England of badly administered poor laws, and the still worse effect in Ireland of a bad system of tenancy, in rendering agricultural labour slack and ineffective. No improvements operate more directly upon the productiveness of labour, than those in the tenure of farms, and in the laws relating to landed property. The breaking up of entails, the cheapening of the transfer of property, and whatever else promotes the natural tendency of land in a system of freedom, to pass out of hands which can make little of it into those which can make more; the substitution of long leases for tenancy at will, and of any tolerable system of tenancy whatever for the wretched cottier system; above all, the acquisition of a permanent interest in the soil by the cultivators of it; all these things are as real, and some of them as great, improvements in production, as the invention of the spinning jenny or the steam-engine.
We may say the same of improvements in education. The intelligence of the workman is a most important element in the productiveness of labour. So low, in some of the most civilized countries, is the present  standard of intelligence, that there is hardly any source from which a more indefinite amount of improvement may be looked for in productive power, than by endowing with brains those who now have only hands. The carefulness, economy, and general trustworthiness of labourers are as important as their intelligence. Friendly relations, and a community of interest and feeling between labourers and employers, are eminently so: I should rather say, would be: for I know not where any such sentiment of friendly alliance now exists. Nor is it only in the labouring class that improvement of mind and character operates with beneficial effect even on industry. In the rich and idle classes, increased mental energy, more solid instruction, and stronger feelings of conscience, public spirit, or philanthropy, would qualify them to originate and promote the most valuable improvements, both in the economical resources of their country, and in its institutions and customs. To look no further than the most obvious phenomena; the backwardness of French agriculture in the precise points in which benefit might be expected from the influence of an educated class, is partly accounted for by the exclusive devotion of the richer landed proprietors to town interests and town pleasures. There is scarcely any possible amelioration of human affairs which would not, among its other benefits, have a favourable operation, direct or indirect, upon the productiveness of industry. The intensity of devotion to industrial occupations would indeed in many cases be moderated by a more liberal and genial mental culture, but the labour actually bestowed on those occupations would almost always be rendered more effective.
Before pointing out the principal inferences to be drawn from the nature of the two antagonist forces by which the productiveness of agricultural industry is determined, we must observe that what we have said of agriculture, is true with little variation, of the other occupations which it represents; of all the arts which extract materials from the globe. Mining industry, for example, usually yields an increase of produce at a more than proportional increase of expense. It does worse, for even its customary annual produce requires to be extracted by a greater and greater expenditure of labour and capital. As a mine does not reproduce the coal or ore taken from it, not only are all mines at last exhausted, but even when they as yet show no signs of exhaustion, they must be worked at a continually increasing cost; shafts must be sunk deeper, galleries driven farther, greater power applied to keep them clear of water; the produce must be lifted from a greater depth, or conveyed a greater distance. The law of diminishing return applies therefore to mining, in a still more unqualified sense than to agriculture: but the antagonizing agency, that of improvements in production, also applies in a still greater degree. Mining operations are more susceptible of mechanical improvements than agricultural: the first great application of the steam-engine was to mining; and there are unlimited possibilities of improvement in the chemical processes by which the metals are extracted. There is another contingency, of no unfrequent occurrence, which avails to counterbalance the progress of all existing mines towards exhaustion: this is, the discovery of new ones, equal or superior in richness.
To resume; all natural agents which are limited in quantity, are not only limited in their ultimate productive power, but, long before that power is stretched to the utmost, they yield to any additional demands on progressively harder terms. This law may however be suspended, or temporarily controlled, by whatever adds to the general power of mankind over nature; and especially by any extension of their knowledge, and their consequent command, of the properties and powers of natural agents.1
[1.][From the 6th ed. (1865) was first omitted the following explanatory clause of the original: “as soon, in fact, as men have applied themselves to cultivation with any energy, and have brought to it any tolerable tools.”]
[∗.]Letters from America, by John Robert Godley, vol. i. p. 42, See also Lyell's Travels in America, vol. ii. p. 83,
[1.][The account of Carey's argument, occupying this and the next two paragraphs, took the place in the 6th ed. (1865) of the brief paragraph referring, without mentioning any name, to the assertion that “the returns from land are greater in an advanced, than in an early, stage of cultivation—when much capital, than when little, is applied to agriculture.]
[∗.]Ireland may be alleged as an exception; a large fraction of the entire soil of that country being still  incapable of cultivation for want of drainage. But though Ireland is an old country, unfortunate social and political circumstances have kept it a poor and backward one. Neither is it at all certain that the bogs of Ireland, if drained and brought under tillage, would take their place along with Mr. Carey's fertile river bottoms, or among any but the poorer soils.
[1.][See Appendix J. The Law of Diminishing Return.]