This section is from the "Economics In Two Volumes: Volume I. Economic Principles" book, by Frank A. Fetter. Also available from Amazon: Economic
§ 10. Rhythmic changes of population. Changes in population are constant. Until recently these changes have generally been of a rhythmic nature. Again and again, in the history of savage races, the failure of a single crop, war, or a plague would reduce a population in a few years much below a former level. This loss usually would be recovered within the next one or two generations. An enormous loss of population, however, such as that from the Black Plague in England in the fourteenth century, might rarely cause returns to the laborer to increase so greatly that the effects were not lost for a century. War, invasion, immigration, would reduce or add to the population of each country, yet on the whole the density of population would continue on about the same level from century to century. Good rulers and bad came and went and the education varied above and below a certain average. The amount of rainfall in some localities or in whole countries rises and falls in a pretty regular cycle of eight to ten years, more or less, causing food supplies to vary, as in the seven fat years and the seven lean years of biblical Egypt. The conditions for special crops, such as frost, snow, sun, cloudiness, hail, vary from year to year; and many insect pests run in cycles alternating with the insects' food supply and parasitic enemies. In a larger view the rise of labor-incomes that resulted from the opening of America and with the agricultural improvement of the last century may prove to be only rhythmic, not cumulative. In so far as a rapid increase of population results, incomes are again lowered toward the former level.
§ 11. Cumulative dynamic economy. The growth of population in European and American countries in the past hundred years has gone steadily onward, not canceled by losses. The addition made to numbers (tho not necessarily a further continuation of the growth) is at least for a long period to come, a permanent fact. The movement is doubtless partly, but not wholly, rhythmic, and if a future decrease comes it is likely to result from different causes. This growth of population has gone along with other changes of an equally enduring character. Of this kind is the great increase of area open to settlement by the advanced industrial peoples, the permanent displacement on a whole continent of the savage, hunting economy and its inefficient methods of food production - the improvement of transportation opening up new sources of materials and foods to the older countries, and the rapid consumption of our supplies of timber, coal, and other mineral resources for which substitutes are difficult if not impossible to find.
§ 12. Individual and general adjustment to static conditions. In every economic situation there is involved an equilibrium of values and prices. It is the theoretically correct set of prices and incomes - not what we might wish to see but what logically results from the presence of men, desires, and goods as they are. In this equilibrium and in the movements bringing it about, there are two kinds or aspects of adjustment to be observed, the individual adjustment and the general adjustment. Each individual, it may be assumed, moves toward the occupation that (as conditions are, which he can not alter) offers him the best return (theory of wages), and uses his agents (theory of usance) so that they give the best return he knows how to obtain. If no new force is introduced and existing forces are permitted to work themselves out, a static equilibrium will result and will continue unchanged. The principle of proportionality would apply to all the combinations of factors in this equilibrium. At the prevailing prices and with the prevailing methods, so much labor of a certain kind should be used with so many agents of various kinds. If either more or less of any factor is used, the result is a product of less value for the costs and hence yielding a smaller profit (theory of profits). If a new method or a new proportion is found to be better, this is a new dynamic element. But if the theoretic, static equilibrium has been attained, there is no chance to increase the yield except when correcting a previous error by which the ideal adjustment was missed. The individual having found what seems the best adjustment has only to hold steadily to it.
Underlying each individual's adjustment is the general adjustment of prices and yields. Under these conditions not only this workman but all like workmen can get such an amount of real wages; not only this bushel of wheat and bale of cotton bring the price, but all other like units do the same; not only this acre of land, but all other like acres of land will have equal values and uses. The individual in making his adjustment is simply trying to get into line with the general situation, to find his true place on the various levels of prices made possible by the totality of conditions.
§ 13. Adjustment to dynamic forces. In a dynamic situation the adjustment still has the two aspects. The individual workman, the passive capitalist, and the enterpriser are all endeavoring to attain to an ideal adjustment inherent in the new situation. We have already seen in many connections and in many examples how profits and losses multiply in dynamic conditions.9 Every dynamic force in industry unsettles an equilibrium, makes some factor more or less plentiful, technically efficient, and valuable. The new ideal adjustment must be made quickly and correctly. Sometimes using more of a factor than before yields a larger profit, sometimes using less may do so. The general adjustment that goes on in dynamic conditions is most important because it involves not merely the change of this or that personal fortune, but the raising or lowering of the real incomes for whole sections and classes of the population, and therefore alters the general economic welfare.
Various meanings of diminishing returns. The chief other meanings given to the phrase law of diminishing returns, which must be deemed to be more or less confused and erroneous, will here be noted.
It is confused with the law of proportionality or with the law of enterpriser's cost, especially as applied to the use of land in agriculture. The fact that a farmer can not profitably employ an unlimited amount of labor in any one year on a single acre is said to be due to the law of diminishing returns. A like application of the term is made in explaining the limitation in the use of land for other purposes, residence, etc. (see above, the principle of proportionality, ch. 12). This application is still further extended to the use of all other kinds of agents. Later and exacter criticism (notably Edwin Cannan, in "Production and Distribution," 1894) has discerned that more than one problem is involved (which he called technical and historical diminishing returns). In our view there are at least three distinct problems: (1) technical proportion, the best mechanical or physical combination; (2) profitable proportion, the enterpriser's best combination of factors at existing prices; (3) diminishing returns, the social-economic problem of the relation of population to resources.
The converse phrase, law of increasing returns, is applied to the economy of large production, especially in the common contrast between manufacturing, said to be subject to the law of increasing returns, and farming, said to be subject to decreasing returns. There is error here at every point. The manufacturing enterprise as it grows is assumed to enlarge the area of land, as it is needed (problem of investment in large production), whereas the farm is taken as a fixed area (problem of proportionality). This appears to have been first clearly pointed out by J. R. Commons in his "Distribution of Wealth," 1895.
9 See ch. 27, sec. 13, note.