§ 8. Tendency versus actuality. "Tendency" of population does not mean here an actual movement, for self-evidently population could not increase in such a ratio, for each individual mouth must have additional food. When population has reached 2 its rate must slacken, for one fourth of the total population in the next period would starve, or, distributing the food evenly, all would have to live on an even scantier diet, until pestilence, the effect of want, reduced the numbers. "Tendency" in respect to population meant latent possibility of the population reproducing and multiplying itself provided food increase kept pace; tendency in respect to food meant actual possibilities of the food being increased by the additional hands working on the same area of land.

Bearing in mind this ambiguity the principle may be expressed apart from the two ratios as follows. Population has a tendency to outstrip means of subsistence, with the result of poverty, misery, and famine. Tendency here if carefully examined is seen to be a very complex idea, neither a simple force, nor an actual increase of numbers, but a combination of the physiological maximum of birth rate, of the natural unlimited philoprogenitive impulse, and of adequate care and sustenance to rear the enormous number of children that would be born under these supposed conditions. But there can not be food enough, hence misery and death. " Tendency" is what would happen if there were food enough, but in reality population can not increase beyond 2, the limit of the food supply. Likewise, in reality, the food can not increase beyond 2, for the increase of food from 2 to 3 is merely what would happen if twice as many hands could be put to work upon the same area, as in fact they can not be. Hence it is implied in the argument of Malthus (tho he does not clearly express it) that there is in any country a natural point of equilibrium between population and food which in the figures he has chosen as illustrations must be at 2 and 2. Evidently the food supply depends upon the stage of the arts of food production. As society changes from hunting to agriculture, from hand culture to plowing, etc., the food possible on the same area with the same labor increases, but population would quickly increase to this new equilibrium, of 3, 3, or 4, 4, etc. Population can not actually increase much beyond that point, for disease and other ills will then set in and again reduce the numbers.

Hence in Malthus' view the law of population, expressing the relation of the number of people to the actual food, is essentially rhythmically static. Population moves in cycles up to and slightly beyond the quantity of food it can produce, then is cut down by some catastrophe, and again slowly rises to the former equilibrium. Any margin, or surplus of food production made possible by a cumulative dynamic force changes the normal static level around which population thereafter oscillates. Malthus shows by many historical examples how again and again war, or the chance failure of crops, or pestilence has greatly reduced the population of a country, and how almost invariably this loss has been made up by a rapid increase in numbers in a single generation up to the limit of the food supply, followed by another period of stationary numbers.

§ 9. Food limit versus moral restraint. Another notion very unclearly expressed and doubtless very cloudy in the mind of Malthus was the nature of this limit of the food supply. He assumes that there is such a limit at each time and country, but nowhere carefully analyzes the idea. He vaguely implies that it is all the food that the people can get, and his principle of population usually has a materialistic, a fatalistic character, with its picture of a limited food supply predetermined, in a way not quite clear, by forces outside of the choice and control of men, and setting the subsistence limit to the total population.

Yet in making his main argument against communism he shows that at least those families with private property do not put their whole incomes into food, but keep their numbers down, and direct toward other things than food a large part of the agents they control. This choice, or quality of mind, is recognized in the first edition of the essay and in the second edition is named moral restraint. A psychological factor enters here to take a place alongside of the materialistic factor, and the two never are reconciled by Malthus. Moral restraint, Malthus seems to think, is limited to a small section of the population, does not act upon the masses, and plays no appreciable part in explaining the total population of the country. He still thinks of population on the whole as regulated by the food supply. Yet Malthus does not think it useless to advise the working classes for their own welfare to postpone marriage and thus limit the size of their families. This notion became the starting point for the propaganda called neo-Malthusianism (which has advocated proposals very different from that of Malthus) to prevent very large families among the working classes.

§ 10. Inadequate recognition of psychic factors. Indeed the work of Malthus is replete with suggestions and with keen observations of history, not sufficiently analyzed or organized, and often expressed in ambiguous terms. The Mal-thusian doctrine of population has been the center of a continuous, and often bitter, controversy ever since its appearance, both as matter of economic theory and as to its bearing upon radical social reforms. Because of the features in it we have just noted it is futile now to line up for or against Malthusianism. Hardly any two persons mean just the same thing by that term. We may agree that Malthus got hold of a great biological principle without understanding its full bearings. Darwin was struck by this in reading Malthus' book, and made it the starting point of his great doctrine of natural selection in explaining evolution. Since 1859, therefore, we are in a position to see the subject in much broader perspective. It is best therefore to put aside from our thoughts prejudices and controversies clustering around the Malthusian doctrine, and to find a basis for a doctrine of population in the ideas of modern biology and psychology and in the statistical facts of our times.

§ 11. The overplus of blossom. A doctrine of population is the grouping and explanation of the various influences that combine to determine the number of people in the several localities and in the world as a whole. The most fundamental fact in the doctrine of population is the surplus of life germs. In every species of living organism, vegetable or animal, the production of germ cells in each generation is vastly greater than the number that develops into living offspring. Yet the number of offspring born is much greater, in most species vastly greater, than would suffice to maintain the number of living individuals undiminished if all the young lived to maturity. Each species has an average or normal birth rate, great or small. Insects produce thousands of eggs each, fish produce hundreds, the rabbit a score of young in a year, and the elephant but one in three years. Clearly there is a general inverse relation between the intelligent care that the parents of any species give to their offspring, and the number of life germs produced. Nature economizes the forces of the species by a gradual reduction of the real surplus, but always leaves what the engineers call a "factor of safety." There are so many chances of accident, that if the number of germs is enough only in favorable conditions, the species will become extinct under any conditions in the least unfavorable.