United States, and even in Massachusetts, the population as a whole is increasing, but the increase is confined for the most part apparently to the immigrating classes. Inasmuch as the failure to increase is confined to only a part of the population in the United States, it is extremely difficult to ascertain the exact situation by statistical means. An insidious loss may be going on in a particular direction and still be undiscovered because of defective mortality statistics.
These statistics put the whole native population of Massachusetts in the same position as college graduates, and the question accordingly seems to be one of the upper class or of the older part of the population and not simply a question of the educated classes.
In the absence of further statistics upon the subject, it will be of assistance to ascertain, by theoretical law if possible, the causes which contribute to these suicidal tendencies in the population. Laws of population have been formulated from similar experiences in other countries, and among these laws we may find one which will throw light upon our own situation.
It will not be worth while to review the common theories of population and show their application to our present conditions. The theory of Malthus, or even that of Spencer, will be of little avail, as the birth rate in the United States is not greatly affected by physical causes. And, although some writers have pointed to a possible biological cause, it is improbable that in a new country like the United States even the older part of the population could, as a class, be losing its fertility, when in so many of the older countries the fertility of the population is still good.
To social causes, primarily, are due the differences in the fecundity of civilized peoples. Therefore I shall present what may be called a social law of population. From the nature of the case any law of population must be exceedingly general, because a great number of conditions directly or indirectly affect the birth rate, and these secondary causes differ in different localities. The law which I am about to consider explains the situation only in a general way. Some of the special conditions which affect the birth rate here I shall discuss later on. This law of population is one formulated by a French student of demography, Arséne Dumont. In brief M. Dumont's theory is that population increases inversely with 'social capillarity.' This expressive phrase is almost self-explanatory. Among progressive peoples a strong tendency exists for men to improve their condition, and in a democratic country society yields somewhat to efforts in this line. If competition is severe it will be necessary for men to make a great effort to raise their standard of living, or sometimes, even to maintain the accustomed standard. Population is regulated by the intensity of the effort made.
