From http://en.wikipedia.org/wiki/Thomas_Robert_Malthus
Malthus argued that two types of checks hold population within resource limits: positive checks, which raise the death rate; and preventive ones, which lower the birth rate. The positive checks include hunger, disease and war; the preventive checks, abortion, birth control, prostitution, postponement of marriage and celibacy.[26] Regarding possibilities for freeing man from these limits, Malthus argued against a variety of imaginable solutions.
Malthus thought these things were good, because keeping things within resource limits is good, because if you don’t, then there’s starvation.
Liberals call it the Malthus Problem, or something like that. They want some sort of socially engineered society, which is actually going to be miserable, but they know that without major population control, their schemes will fail, because the natural order without things like war, poverty, etc, there would be mass famine. Social Engineering to get rid of war and poverty fails because of the Malthus problem.
Marx repeated the lie, adding that Malthus had taken the vow of celibacy, and called him “superficial”, “a professional plagiarist”, “the agent of the landed aristocracy”, “a paid advocate” and “the principal enemy of the people.”
One very simple observation that the left ignores and it will be catastrophic. the Social Engineering using 'preventive checks' can only work with governments that have this in place. Those that don't will continue to grow to their own limits. Then they will flood those countries that doesn't have sustained populations.
In my book Social Engineering is Social suicide.