I’m currently reading Selfish Reasons to Have More Kids by Bryan Caplan. The principal argument of the book is that parents in developed countries can have more children than they are currently having without incurring costs themselves or imposing (substantial) costs on others, and therefore should do so. One of Caplan’s premises is that, excluding any externalities that having a child might produce, it is moral to have a child for the simple reason that you are giving life to someone who otherwise wouldn’t be alive. To illustrate, during the course of his discussion of IVF, Caplan writes, “It is good to exist. The clearest beneficiary of any life-giving technology is the child himself, who would almost certainly be glad to be alive.” In this post, I want to briefly discuss an interesting implication of Caplan’s premise.
In the book, Caplan—based on Julian Simon’s argument from The Ultimate Resource—assumes that, on average, having a child produces an externality with a zero or positive sign. However, he acknowledges there are situations outside the average where having a child produces a negative externality. To take a very simple case, he writes, “According to the Korean adoption study, for example, Mary’s firstborn child will finish six fewer months of education because she gave him four siblings.” Assuming (somewhat unrealistically) that the education externality conferred by siblings is linear, each additional sibling reduces the firstborn’s total education by 1.5 months.
The natural-rights conception of morality asserts that it is immoral to violate someone else’s natural-rights, say by conferring a negative externality on her. Under this conception of morality, regardless of any inherent positive good having a child does, it is immoral to have one if doing so confers a negative externality on at least one person.
In contrast, the utilitarian view of morality asserts that it is immoral to take any action that does more harm than good, produces more pain than pleasure, or yields more preference-dissatisfaction than preference-satisfaction. Under this view of morality, the implications of Caplan’s premise are slightly more interesting. In particular, if having a child confers a net negative externality then whether one should have a child depends on the relative sizes of the net negative externality and the inherent positive good. If the latter is greater than the former, one should have a child; otherwise one should not. Caplan does not specify how much inherent good he thinks giving someone life does, so it is not clear how large the negative externality would need to be to make having a child immoral. In any case, it follows that moral behaviour will generate higher costs for third parties in a moral universe where Caplan’s premise is true than in a moral universe where having a child does not do any inherent positive good.
Incidentally, the book is highly readable and cites lots of interesting research. Finally, David Friedman has an interesting post about externalities from having children here.