In a world that does not recognize equal rights to natural opportunities, having children is a more private decision than when equal rights to natural opportunities are recognized. If a child comes into the world with a right only to the product of his or her labor, then there are few externalities of the decisions people make about how many children to have. Having more children might reduce the level of wages, but the consequent harm to sellers of labor services is offset by the benefit to the buyers of labor services.

On the other hand, if all persons are recognized as having equal rights to natural opportunities, then a larger number of children means less land and natural resources per person for all the people born previously. This may be offset at least partially by the greater economies of scale that are available when there are more people, but there will still be a range of population growth over which each decision by a couple to have a child reduces the real incomes of everyone else. Define such a circumstance as a scarcity of parenting opportunities.

If parenting opportunities are scarce and all nations have populations that grow at the same rate, then any issues of the cost of having children are internal to each nation. Each nation is free to divide the cost of additional children between the parents and the rest of society in whatever way expresses their sense of community. On the other hand, when nations have populations that grow at different rates and parenting opportunities are scarce, issues of justice among nations arise. The children of a rapidly growing nation will be able to say, "Our numbers are greater than those of our parents, so we deserve a greater share of the rent of land and natural resources than our parents received."

It would not be just for the rest of the world to say, "That's not our fault. Your parents had too many children. You must now get by with smaller shares of natural opportunities than the rest of us." It would not be just because the rights to natural opportunities are equal rights of persons. They are not contingent on having had parents who were not excessively prolific. Thus the issue of justice with respect to population growth arises at the time when different nations decide to have different populations growth rates.

The people of a nation that is growing more slowly than another can justly say to the people of the more rapidly growing nation, "By your decision to have so many children, you are increasing the resources that we must set aside to ensure that our children have opportunities at least as satisfying as the ones we enjoy. You owe us something for your disproportionate appropriation of the world's scarce parenting opportunities." Thus the cost (or benefit) that one nation imposes on others by its differential population growth rate would be included in the calculation of the nation's total appropriation of natural opportunities, and therefore in the equalization payment that the nation received or paid.  ... Read the entire article