Malthus and His Critics

In one line

Malthus argued that population grows faster than the food supply and is therefore always checked by misery, and the two centuries since have shown that he was wrong about the mechanism and may not be wrong about the limit.

In the wording a student can write in an exam: Thomas Robert Malthus, in his Essay on the Principle of Population of 1798, argued that population, when unchecked, increases in a geometrical ratio while subsistence increases only in an arithmetical ratio, so that population must always press against the means of subsistence and be held in check either by preventive checks, being restraint on marriage and reproduction, or by positive checks, being famine, disease and war. The argument is the intellectual origin of the position that population growth is the driver of environmental pressure.

The argument

The two ratios. Population, unchecked, doubles at a constant interval, which is geometrical growth. Subsistence, being food from a fixed quantity of land, can be increased only by adding a further increment, which is arithmetical growth. A geometrical series overtakes an arithmetical one however favourable the starting position.

The checks. Because the two cannot both continue, population is held down. Preventive checks are those operating on the birth rate: late marriage, celibacy, what Malthus called moral restraint. Positive checks are those operating on the death rate: famine, epidemic disease, war, and the ordinary misery of the very poor.

The conclusion. Poverty is not an accident of distribution but a necessary consequence of the relationship between the two ratios, and measures that relieve the poor without restraining their numbers make the position worse by permitting further growth.

Why it matters here. That last proposition is what makes Malthus an environmental argument rather than merely an economic one. Substitute any finite resource for subsistence, and the structure is identical: the resource is fixed or grows slowly, the demand grows geometrically, and the collision is only a matter of time.

The neo-Malthusians

The argument was restated in the twentieth century with the environment rather than food as the limit.

The Club of Rome's report of 1972, The Limits to Growth, modelled population, industrial output, food, resources and pollution and concluded that continued exponential growth on a finite planet would produce overshoot and collapse within a century. It was published in the year of the Stockholm Conference and it framed a great deal of the debate there.

The ecological version. The limit is not food but the capacity of the biosphere to supply resources and absorb waste, which is the subject of the next chapter.

The population bomb literature of the same period predicted mass famine, and its predictions did not occur, which is the strongest single point against the neo-Malthusian position.