On Clark And Caplan
[Bryan] Caplan [says] … children impose not costs, but benefits, on the rest of society. …. I think Caplan’s … proposition will soon prove to have applied only in a limited historical window. Future population increases will likely exert substantial downward pressure on the growth of living standards. … There is thus a race between resource costs and scale economies as population grows. … For 99.9% of human history, up till 1800, the winner in that competition was resource scarcity. …
The downward march of food and energy prices since 1800 may well end soon. Current high prices may presage a food scarce-energy scarce future. … Population will again be an important determinant of income. This implies a negative externality associated with fertility, with all the unpleasant implications this holds for those of libertarian persuasion.
Caplan responds:
Clark is right to name economies of scale as one social benefit of population. But he neglects the far more important effect on innovation. … As long as parents are financially responsible for their children, any negative effect of population on living standards is internal to the family. … If parents didn’t care about their already existing children … there might still be a problem. But parents do care about their already existing children. … So it’s unclear whether a problem even exists. … Are you actually willing to bet that global real per-capita GDP will be lower in 2020 than it is today? How about 2030? 2050?
Clark is right that in the long run resource scarcity dominates living standards – that applied for most of human history, and will apply to most of our descendants. Our special dreamtime era of rapid growth and rising living standards can’t last long – probably within a few centuries (and certainly within ten millenia), average consumption will be way down from today.
But Caplan is right that fertility has a net positive externality. Yes property rights are not perfect, so people can hurt each other. But people help each other far more via innovation and scale economies. Yes those will dwindle in the long run, but so will property rights violations.
Of course if you are willing to look only at tiny elites, you can find high average consumption in both the distant past and future. The tiny fraction of future humans who are not robots might well manage to keep a high living average living standard. But most creatures recognizably decended from us will have near subsistence consumption. And that, I think, will mostly be a good thing.
The problem with this is that the beneficiaries of the gains are in this circumstance "new entities," who need not exist and are not harmed by not existing. On the other hand, existing people are harmed by those new people existing and taking away their utility.
In the “long run”, the average human will have only produced subsistence levels of goods and services.
Some will produce more, some will produce less (i.e. will actually destroy goods and services), but the average will be subsistence with no surplus.
The reason I can be so confident of this assertion is that the alternatives are not realistic. We know if the average falls below subsistence levels then humans will become extinct. If the average is above subsistence, then each person contributes (on average) to an ever increasing store of goods and services.
What form does that accumulating surplus take? What accumulated surplus is left from times past? What is the value of that “accumulated surplus”? There are very few artifacts left from the past. Most artifacts have a useful life, when that life is over they must be disposed of at some incremental cost. Once disposed of, there is no accumulated surplus.
What kinds of goods and services could humans produce that would retain value in perpetuity? The Pyramids? Even the Pyramids will eventually wear out.
The only way the average can be positive is if new humans continue to produce more incremental goods and services than they consume. If the average is positive, then eventually humans will be born into a world where the per capita accumulated surplus is many times what they could possibly produce or consume in their lifetime. How do we expect such people to act? Do they only do positive sum transactions where the net accumulated goods and services only increases? Or do they do zero-sum or negative-sum transactions to increase their personal supply of goods and services by exploiting goods and services away from others?
A big problem is that generational transfers can be both positive and negative. There is much concern (actually faux) about the US debt burdening future generations. That would be easy to eliminate administratively. However that is not the only negative transfer to the future that can happen. When global warming melts Greenland and sea level goes up 7 meters, all the assets that are flooded are lost. If there is a spill of toxic material, the spill has to be cleaned up, which has a cost.