But if such be the explanation of rent on land which is the last to be put under cultivation, what is the explanation in the case of better lands? We are not sure that Stuart Mill foresaw this problem.
This is how he explains the emergence of rent on land No. 1. Production having become insufficient to meet demand, prices go up; but it is only when they have reached a certain level—a level, that is to say, sufficiently high to secure a normal return on the capital and labour employed—that these lands will be brought under cultivation.[1176]
The cause of rent in this case is obviously the growth of demand and not the cultivation of land No. 2, because the cultivation only took place when the prices had risen.[1177] Moreover, the effect of this cultivation will be rather to check than to encourage the growth of rent by arresting this upward trend of prices through increasing the quantity of corn on the market. The rent of land No. 1 is consequently a scarcity rent which results directly from an increased demand and is independent of the quality of the land. The real cause of rent on all lands, whether good or bad, is really the same, namely, the insufficiency of supply to meet demand.
A similar process of reasoning might be applied to the other differential rents already mentioned, and the conclusion arrived at is that rent, whatever form it take, is not an anomaly, but a perfectly normal consequence of the general laws of value. Whenever any commodity, from whatever cause, acquires scarcity value and its price exceeds its cost of production, there results a rent for the seller of that product. Such is the general formula, and therein we have a law that is quite independent of the law of diminishing returns and of the unequal fertility of land.[1178]
But the issue was not decided at a single stroke. English political economy is so thoroughly impregnated with Ricardian ideas that it still adheres to the conception of a differential rent. Continental economists, on the other hand, have always regarded it as a more or less natural result of the laws of demand and supply. J. B. Say had long since made the suggestion that the existence of rent is due to the needs of society and the prices which it can afford to pay for its corn.[1179] A German economist of the name of Hermann, a professor at Munich, in his original and suggestive work, Staatswirtschaftliche Untersuchungen, published in 1832, claims that the rent of land is simply a species of the income of fixed capital. Whereas circulating capital, because of its superior mobility, has almost always a uniform rate of interest, fixed capital, which has not that mobility and which cannot be increased with the same facility, has a revenue which is generally greater than that of circulating capital. This surplus revenue or rent, instead of being a mere transitory phenomenon, might easily become permanent provided the new fixed capital which enters into competition with it has a lesser degree of productivity. Such precisely is the case with land.[1180] A little later another German of the name of Mangoldt defined rent as a scarcity price which does not benefit all the factors of production equally, but only those which cannot be readily increased in amount. And rent appears in the guise of a differential revenue simply because scarcity is always relative and is frequently kept in check by substitutes which generally give a smaller margin of profit.[1181] Schäffle, in a work partly devoted to the subject of rent,[1182] published in 1867, insists on the idea that the soil furnishes rent not because it is a gift of nature, but simply because of its immobility and the impossibility either of removing it or of increasing its quantity. Finally, Karl Menger, in his Grundsätze der Volkswirtschaftslehre, published in 1872, in outlining the foundations of the modern doctrine of value, assimilated the theory of rent to the general theory of prices by categorically declaring that “the products of land as far as the nature of their value is concerned afford no exception to the general rule, which applies to the value of the services of a machine or a tool, of a house or a factory, or any other economic good.”[1183]
The only difference, apparently, which recent economists recognise between rents conceived of in this fashion is their greater or lesser duration. The rent furnished by a first-class machine will disappear very readily because new machines can be turned out to compete with it. But when the rent is due to superior natural qualities, whether of land or of men, the element of rent will not be so easily got rid of. To borrow a phrase of Pareto’s, we may say that the rent will be of a more or less permanent character, according to the ease with which savings can be transformed into capital of a more or less durable kind.[1184] Dr. Marshall sums up his subtle analysis of the problem under consideration as follows: “In passing from the free gifts of nature through the more permanent improvements in the soil, to less permanent improvements, to farm and factory buildings, to steam-engines, etc., and finally to the less durable and less slowly made implements we find a continuous series [of rents].”[1185]
The series, we might add, may be extended to a point at which rent becomes negative, i.e. until the conditions of demand and supply become such that the factor of production which previously yielded a supplementary revenue no longer gives even the normal rate of remuneration. Thünen had suggested the possibility of a negative rent, and the idea has been further developed by Pareto.