“Whenever, therefore, there is liberty, the power of increase is exerted; and the superabundant effects are repressed afterward by want of room and nourishment, which is common to plants and animals; and among animals, by their becoming prey of each other” (14). The effects of these checks on humans are more complicated. Thomas Malthus, in his article “An essay on the principle of population”, states that the human population has the tendency to grow. It doubles in 25 years, under favorable circumstances, where food is only the check. In the hypothetical situation, consider the presence of population is a thousand million, the human species would increase as the number 1, 2, 4, 8, 16 … and subsistence as 1, 2, 3, 4, 5 …. In two centuries the population would be to the means of subsistence as 256 to 9 (19).
Supporting his arguments, in Chapter I – “Statement of the Subject. The ratio of Increase of Population and Food”, he writes:
“As by the law of our nature which makes food necessary to the life of man, the population can never actually increase beyond the lowest nourishment capable of supporting it, a strong check on population from the difficulty of acquiring food, must constantly in operation. This difficulty must fall somewhere, and must necessarily be severely felt in some or other of the various forms of misery, or the fear of misery, by a large portion of mankind. It may be safely pronounced, therefore, that the population when unchecked goes on doubling itself every twenty-five years or increase in a geometrical ratio, but the food supply doesn’t seem to double as in the rate of population, hence checking the population to grow in a geometrical ratio. Therefore, it may be fairly pronounced, that, considering the present average state of the earth, the means of subsistence, under the circumstances the most favorable to human industry, could not possible be made to increase faster than in an arithmetical ratio” (15-19).
Malthus, in Chapter II, addresses the want of food as an ultimate check while introduces some more immediate checks such as customs, diseases, molarity, physical nature, etc. He then categorizes these checks to the population under two general heads- the preventive and the positive checks (21). The preventive checks work voluntarily and deal with reasoning while positive checks to population are extremely various, and include every cause, whether arising from vice or misery, which in any degree contributes to shorten the natural duration of human life (21-23). He further lists the example for positive checks as all unwholesome occupations, severe labor and exposure to the seasons, extreme poverty, bad nursing of children, great towns, excess of all kinds, the whole train of common diseases and epidemics, wars, pestilence, plague, and famine (23). “Of the positive checks again, those which appear unavoidably from the laws of nature may be called exclusively misery; and those which we obviously bring upon ourselves such as wars, excess, etc. are brought upon us by vice, and the consequences are misery” (24).
This way Malthus tried linking up all human behaviors together to justify his concept of population and the checks. “Population is necessarily limited by the means of subsistence termed as checks, and these checks are all resolvable into moral restraint, vice, and misery” (28-29).