This phenomenon, the announcement of which has brought down so much abuse on Malthus, appears in truth beyond the reach of doubt.
If you put a thousand mice into a cage, with only as much provision as is necessary for their daily sustenance, their number, in spite of the acknowledged fecundity of the species, can never exceed a thousand, or if it do, there will be privation and there will be suffering,—both tending to reduce the number. In this case it would be correct to say that an external cause limits, not the power of fecundity, but the result of fecundity. There would assuredly be an antagonism between the physiological tendency and the restraining force, and the result would be that the number would be stationary. To prove this, increase gradually the provision until you double it, and you will very soon find two thousand mice in the cage.
And what is the answer which is made to Malthus? He is met with the very fact upon which his theory is founded. The proof, it is said, that the power of reproduction in man is not indefinite, is that in certain countries the population is stationary. If the law of progression were true, if population doubled every twenty-five years, France, which had thirty millions of inhabitants in 1820, would now have more than sixty millions.
Is this logical? [p405]
I begin by proving that the population of France has increased only a fifth in twenty-five years, whilst in other countries it has doubled. I seek for the cause of this; and I find it in the deficiency of space and sustenance. I find that in the existing state of cultivation, population, and national manners and habits, there is a difficulty in creating with sufficient rapidity subsistence for generations that might be born, or for maintaining those that are actually born. I assert that the means of subsistence cannot be doubled—at least that they are not doubled—in France every twenty-five years. This is exactly the aggregate of those negative forces which restrain, as I think, the physiological power—and you bring forward this slowness of multiplication in order to prove that this physiological power has no existence. Such a mode of discussing the question is mere trifling.
Is the argument against the geometrical progression of Malthus more conclusive? Malthus has nowhere asserted that, in point of fact, population increases according to a geometrical progression. He alleges, on the contrary, that the fact is not so, and the subject of his inquiry has reference to the obstacles which hinder it. The progression is brought forward merely as a formula of the organic power of multiplication.
Seeking to discover in what time a given population can double itself, on the assumption that all its wants are supplied, he fixed this period at twenty-five years. He so fixed it, because direct observation had shown him that this state of things actually existed among a people, who, although very far from fulfilling all the conditions of his hypothesis, came nearer the conditions he had assumed than any other—namely, the people of America. This period once found, and the question having always reference to the virtual power of propagation, he lays it down that population has a tendency to increase in a geometrical progression.
This is denied; but the denial is in the teeth of evidence. It may be said, indeed, that the period of doubling may not be everywhere twenty-five years; that it may be thirty, forty, or fifty years; that it varies in different countries and races. All this is fair subject of discussion; but granting this, it certainly cannot be said that, on the hypothesis assumed, the progression is not geometrical. If, in fact, a hundred couples produce two hundred in a given time, why may not two hundred produce four hundred in an equal time?
Because, say the opponents of the theory, multiplication will be restrained.
This is just what Malthus has said. [p406]