Sec. 15. #Population and militarism#.  In view of the recrudescence of the spirit of armed national aggression evident of late, and especially in the outbreak of the Great War in 1914, the military aspect of the population question deserves serious consideration.  The growth of savage and barbarian tribes in numbers, so that their customary standards of living were threatened, frequently has led to the invasion and conquest of their richer neighbors.[18] To-day nations on a higher plane of living are probably repeating history.  The nation with an expanding population is tempted to seek an outlet for its numbers and for its products by entering upon a policy of commercial expansion, which in turn has to be supported by stronger military and naval establishments.  It is led by primitive impulses that to it carry their own moral justification, to possess the territory of its neighbors.  The immediate occasion is probably some matter of internal politics, such as growing discontent and democratic sentiment among the people.  Nations with slowly growing populations, and still possessed of ample territories to maintain their accustomed standards of life, naturally favor the status quo, and are pacifist or nonmilitarist.  If they arm it is for their own safety.  In this view, militarism is seen to consist not in having drilled soldiers and stores of munitions, but in the national state of mind that would use these for aggression, not merely for defense.  When, therefore, a powerful nation has reached a certain stage in the relation of its population to resources, limitation of population not limitation of armaments is the real pacifism; and increase of population, not increased military training or a larger navy, is the real militarism.

Sec. 16. #Problem of maximum military power.# It is a grave question, however, whether a nation with a comparatively sparse population, high wages, and great wealth can safely limit that population in the presence of a capable, ambitious, and efficient rival that covets such opportunities.  On the one hand, a population may be so sparse that it has not soldiers enough to defend its territory against a numerous enemy; on the other hand, it may be so dense, and consequently average incomes be so low, that it cannot properly train, arm, and support its population of military age.  The recent developments in the art of warfare call for great use of the mechanical industries, for great power to endure taxation, and for great financial resources, conditions found only where the average of national income is high.  The point of maximum military power must be far short of the maximum possible population.  It would seem that a nation of 100,000,000 inhabitants favorably situated to resist aggression, well supplied with the natural materials for munitions, and well equipped to produce them, might safely limit its numbers so as to ensure a high level of popular income.  This safety would be greatly increased by permanent alliance with other peoples likewise limiting their numbers and, therefore, interested in maintaining the peace of the world.  In this way it would be possible for them all to maintain a standard of popular well-being even higher than is fully consistent with the maximum military power, even in the presence of prolific and aggressive rival nations.