Biology furnishes no reason for believing that the competition among nations must always remain a crude physical struggle, and that the substitution of “rational” for “natural” selection among individual members of a nation cannot be extended to the selection of nations and of races.
V
The history of past nations indeed gives an appearance of natural necessity to imperial expansion and to the military policy which is its instrument, and many who deplore this necessity accept it. A recent American writer in a brilliant monograph [51] argues the perpetual necessity of wars of conquest and of the Imperialism which such wars express, as following from “the law of decreasing returns.” A population on a limited area of land not only tends to grow but actually grows faster than the food supply that is available; improvement in the arts of cultivation does not enable a people to obtain full subsistence for its growing population, hence a natural and necessary pressure for access to new rich land, and conflicts with and victories over neighbours who seek to hold their own, or are even actuated by the same needs of territorial expansion. Hunger is a necessary spur to migration, and where emigrants, planting themselves successfully upon new fertile lands, formerly unoccupied or occupied by people whom they have subjugated, desire to retain the political union with the mother country, an unlimited expansion of national areas ensues. Whether such expansion takes shape in genuine colonisation or in what is here properly distinguished as Imperialism, involving centralised government and forcible control of “inferior races,” matters little to this wide argument. The essence of this policy is the acquisition of an expanding area for food supply. A nation with growing population must either send a constant