The insoluble problem of population

The world population is currently more than two and a half times what it was when my parents were born. It can’t keep on growing forever.


One point of view is that as the population continues to grow, technology will grow apace — so that, no matter how high the figures climb, human ingenuity will always find a way to make sure there is enough food, water, oxygen, and living space to go around.

Obviously that can’t be true. Maybe the earth can be made to support a very large number of people — trillions, say — but it can’t support an arbitrarily large number. There must be a limit somewhere. Sooner or later, if the population continues to grow, we will reach that limit.

And long before we reach the point where it is physically impossible for the earth to support us, we will reach the point — many countries have reached it already — where population density begins to have a negative effect on the quality of life. No one wants to live on a planet — or in a country — which is filled to capacity, where there is no extra space, no countryside, no wilderness, not even any backyards or roomy living rooms. Living in Taiwan (with 19 times the population density of the U.S.), I’ve had a little foretaste of that, and it isn’t very nice.

Nor is space colonization a viable solution. Even assuming it were technically feasible, uprooting a few billion people every generation or two and shipping them off to other planets isn’t going to do much for our quality of life either.


Another “optimistic” point of view is that the problem will solve — is solving — itself, as more and more peoples voluntarily choose sub-replacement fertility. In most of the developed world, population growth rates are low or even negative, and what growth there is comes more from immigration than from the reproduction of the indigenous population. And the developing world is, as the euphemism implies, assumed to be developing. That is, given time, it will become “developed” and stop reproducing.

But such a situation is evolutionarily unstable and cannot possibly be permanent. So long as there is variation in fertility rates, and so long as that variation is correlated with heritable (genetic) or quasi-heritable (religious) features, those who reproduce at above-replacement levels will multiply at the expense of those who do not, and overall rates of population growth will go back up.


Since voluntary population control cannot by its nature be a long-term solution, that leaves Chinese-style coercive population control — which is obviously morally unacceptable. To be effective, it would have to be applied to the entire world, and it would have to be strictly enforced — meaning, in practice, forced abortion or infanticide. Without strict, universal enforcement, it would be no more stable than voluntary control. Some people would inevitably go on reproducing, regardless of social pressure or sanctions, and whatever it was that made them do so, they would be likely to pass it on to the next generation — leading in the long term to rising fertility.


So there’s no solution at all.


Filed under Politics, Science

3 responses to “The insoluble problem of population

  1. Samson J.

    Great post, WMJ; a topic I’ve given some thought to as well. The tension between being pro-life but also pro-sustainability is one of the few key issues I haven’t resolved for myself yet, within my own personal philosophy.

    we will reach the point — many countries have reached it already — where population density begins to have a negative effect on the quality of life.

    “Many countries” indeed. I would strongly argue that the United States is well beyond this point!

    You may laugh, but it depends on what you value. Contrast, for instance, the vast amount of farmland available to early settlers with the difficulty of affording even a small piece of acreage in some states today. This is a big deal if, like me, you think the Republic was at its best when most people were free yeoman farmers.

    Another example I can think of deals with hunting, which you may not be aware of if you aren’t into hunting or fishing. It’s a problem we don’t usually have up here in Canada, but certainly I’ve dialogued online with Americans who complain about it, which is the fact that in many states there just is no public land on which to enjoy these outdoors activities, because everything is owned and “posted”, as they say, with no-trespassing signs.

    There are other adverse effects, too. I personally happen to believe that a “nation” cannot remain politically and socially cohesive if its population is too large; beyond a certain number of citizens, people just don’t feel connected; there is no common bond holding them together. I don’t know where I’d put the ceiling on this but certainly 300 million is (at least) an order of magnitude too high.

    So there’s no solution at all.

    That’s where I’m at currently, as well. Nice to know you’ve followed the same train of logic I have. Sometimes I think, well, it’s not up to us to figure out a solution anyhow, so let’s just sit back and enjoy seeing how it unfolds, from a scientific perspective.

    Of course, it may depend on one’s religious point of view. I’m not one to advocate the idea that “we don’t need to worry, because God will sort it all out before anything Really Bad happens,” but I do think there must have been some kind of divine plan regarding all this.

  2. it isnt the only outcome – extinction is a possibility (in theory) – and after selection has gone on for a while, humans may change and become something else (leaving aside religious possibilities and prophecies).

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