It must be noticed that if the absence of exact numerical data be alleged as an excuse for the superficial dealing with economic matters of which we spoke previously—this is no excuse at all.
In the domain of exact sciences we know very many cases where two quantities depend upon each other, so that if one of them increases, the other increases as well—and yet we know that they are not proportional to each other. The rapidity of growth of a plant certainly depends, among other causes, upon the quantity of heat it obtains. Both the height of the sun above the horizon and the average temperature of every separate day (deduced from many years' observations) increase every day after March 22. The recoil of a gun increases when we increase the quantity of powder in the cartridge. And so on.
But where is the man of science who, after having noticed these relations, would conclude that consequently the rapidity of growth of the plant and the quantity of heat it receives, "the height of the sun above the horizon and the average daily temperature, the recoil of the gun and the quantity of powder in the cartridge are proportional? that, if one of the two increases twice, or thrice, the other will increase at the same ratio? in other words, that the one is the measure of the other? A man of science knows that thousands of other relations, besides that of proportionality, may exist between the two quantities; and unless he has made a number of measurements which prove that such a relation of simple proportionality exists, nobody will ever dare to make such an affirmation.
Yet this is what economists do, when they say that labour is the measure of value! Worse than that, they even do not see that they only make a mere suggestion, a guess. They boldly affirm that their affirmation is a Law; they even do not understand the need of verifying it by measurements.
In reality, the relations between such quantities as the growth of a plant and the heat it receives, the quantity of powder burned and the recoil of a gun, etc., are too complicated to be expressed by a mere arithmetical proportion. And this is also the case with the relation between Labour and Value. Value in exchange and the necessary Labour are not proportional to each other; Labour is not the measure of Value, and Adam Smith had already noticed it. After having begun by stating it was, he soon noticed that this was true only in the tribal stage of mankind. Under the capitalist system, value in exchange is measured no more by the amount of necessary labour. Many
