Bryan Caplan is an economist and a dad who has thought a lot about the joys and stresses of being a parent. When I asked him whether there is an ideal number of children to have, from the perspective of parents’ well-being, he gave a perfectly sensible response: “I’m tempted to start with the evasive economist answer of ‘Well, there’s an optimal number given your preferences.’” When I pressed him, he was willing to play along: “If you have a typical level of American enjoyment of children and you’re willing to actually adjust your parenting to the evidence on what matters, then I’ll say the right answer is four.”
Four does happen to be the number of children Caplan himself has. But he has a rationale for why that number might apply more generally. His interpretation of the research on parenting, which he outlines in his 2011 book, Selfish Reasons to Have More Kids
In other words, many parents make parenting unnecessarily dreadful, so maybe, Caplan suggests, they should revisit their child-rearing approach and then, if they can afford to, consider having more kids, because kids can be fun and fulfilling. No sophisticated math brought him to the number four. “It’s just based upon my sense of how much people intrinsically like kids compared to how much needless suffering they’re doing,” he said. Caplan even suspects that more than four would be optimal for him.