Herbert Spencer

by J. Arthur Thomson

But while the rate of reproduction depends upon the constitution of the individual organism, modifiable within variable limits by the direct influence of food, warmth, and the like, the rate of increase or decrease in an animal or plant population depends upon the wide and complex conditions of the entire animate and inanimate environment. In short, it is a function of the Struggle for Existence.

When there are no checks to prolific multiplication a single Infusorian may become, in the course of a week, the ancestor of several millions, and the same is true of a Bacterium within a day. Huxley has computed that the progeny of single mother Aphis or green-fly, if they all lived a charmed life, would in a few months literally outweigh the population of China, which probably amounts to between two and three hundred millions. If there were no checks to increase, a few pairs of cod-fish and conger-eels would soon put an end to fishing and much else, by making the North Sea solid. And apart from problematical cases, every now and then, with locusts or voles, with rabbits in Australia, or sparrows in America, we get a vivid glimpse of what a "spate" of life may mean.

In the main, however, the river of life overflows its banks only locally and temporarily. An adjustment of the abundance of life to the limitations of subsistence is speedily effected in nature, and the flood subsides. The "positive checks" of disease, starvation, lack of room, internecine competition, increase of enemies, and so on, re-establish a balance, though perhaps with a slightly changed centre of gravity. The struggle for existence punctuates the increase of population.

In the history of mankind various aspects of the population question are familiar. Whether we inquire into what is known of the history of uncivilised races, or into present-day conditions in more or less isolated communities and even in large countries, we read the story of population-crises—of increase in numbers out-running the means of livelihood. Among races in contact one often increases at a much more rapid rate than the other, and we hear of "perils" of various colours. Within a given race we find great differences in the fertility of different sections or stocks and dangerous results impending. One nation is troubled by its teeming millions, and another by its dwindling birth-rate. The whole question is one of great biological interest and human importance, and it is one to which Spencer had a very definite contribution to make.

But before we consider Spencer's theory, it may be profitable to notice what other suggestions have been made.

(a) Malthusian.—In 1798, in his Theory of Population, Malthus riveted the attention of all thoughtful men by seeking to establish the induction that population tends to outrun the means of subsistence. In its earliest form, his thesis was that population tends to increase in geometrical ratio, while the means of subsistence increase only in arithmetical ratio. So precise a statement cannot be justified, but Malthus was right in insisting on the general fact that in certain conditions and in certain stocks multiplication tends to exceed the means of subsistence. His discussion of this thesis, and the conception of "the struggle for existence" which he developed—for the phrase was his—had a profound influence on many minds, including Spencer, Darwin, and Wallace.

Malthus pointed out, with abundant concrete illustration, that the increase of population is met by "positive checks," such as disease, starvation, war, and infanticide, and that it may also be met by "prudential checks," such as late marriage and moral control. His practical corollary was that to avoid the "positive checks" which are almost always appalling and pity-moving, we must develop the "prudential checks," which tend to prevent further swelling of the population-tide. "To a rational being the prudential check to population ought to be considered as equally natural with the check from poverty and premature mortality" (Malthus, 1806). The obvious objections are, that extended celibacy or postponed marriage tends to increase of sexual vice; that very late marriages are biologically and psychologically inadvisable, tending for instance on an average to increased mortality in childbirth, to less fit children, and to a diminution of the happiness of married life; and that moral control is apt to be most exercised where it is least needed, namely among the more highly developed stocks, and that it is a very uncertain check since great conjugal temperance seems often to render conception the more certain.

(b) Darwinian.—The Darwinian theory, that is the theory of Natural Selection, supplied an important supplement to the Malthusian position. For it pointed to the course of nature wherein the struggle for existence has opened up the pathway of progress. Increase of population brings about or accentuates the struggle for existence wherein the relatively less fit are eliminated. Although this Natural Selection works slowly it works surely, hence the Darwinian corollary is practically nil, that is to say, a laissez-faire policy. The obvious objections are, that man as a rational and social being has a higher standard than mere survival, and that a confidence in uncontrolled natural selection is altogether optimistic. He cannot abrogate his task of endeavouring, by rational selection, to accelerate what he believes to be progressive evolution and to hinder degenerative change. Moreover, it is not in him to stand by contemplating the mills of Nature grinding slowly, ignoring the well-being of the individual in considering the merely possible advancement of the species. And as a matter of fact he is continually interfering with natural selection by introducing various modes of what he believes to be rational selection.

(c) Neo-Malthusian.—The general position of modern Malthusians may be summed up in a few propositions. Population has a constant tendency to outrun the means of subsistence; over-population is a fruitful source of pauperism, ignorance, crime and disease; the positive or life-destroying checks are cruel, and their reduction is in the line of social progress; abstention from marriage is for normal organisms unnatural and anti-social, postponement of marriage is also unnatural and tends to vice and unfitness; the check that remains to be advocated is "prudence after marriage," and by this the Neo-Malthusians most distinctly mean attention to methods which secure small families. So far as these scientific checks imply control and conjugal temperance and obviate or lessen misery, they commend themselves, but the obvious objections are, that their use is often not without its physiological risks, and that by annulling the responsibility of consequences, while allowing the gratification of sexual appetites to continue, they may have the result of increasing an already sufficiently intense sexuality, of facilitating unchastity, and of exaggerating the tendency of marriage to sink into "monogamic prostitution." On the other hand, it seems probable that the transition from impulsive animalism to deliberate regulation—somewhat mechanical though it be—would tend in some to decrease not increase sexual intemperance. While the ideal surely is that there should be a retention, throughout married life, of a large measure of that self-control which must always form the organic basis of the enthusiasm and idealism of lovers, it remains a fact that even exemplary temperance does not obviate an unduly large family, and that some form of Neo-Malthusian practice is in many cases the only practicable suggestion—pis aller though it be.

(d) Spencer's Contribution.—In his keen analysis of the conditions of multiplication,[20] Spencer showed that a species cannot be maintained unless self-preservative and reproductive powers vary inversely, and gave a physiological reason why these two powers cannot do other than vary inversely. If we group under the term individuation all those race-preservative processes by which individual life is completed and maintained, and extend the term genesis to include all those processes aiding the formation and perfecting of new individuals, the result of the whole argument may be tersely expressed in the formula—Individuation and Genesis vary inversely. And from this conception important corollaries follow; thus, other things equal, advancing evolution must be accompanied by declining fertility; again, if the difficulties of self-preservation permanently diminish, there will be a permanent increase in the rate of multiplication, and conversely.