Jonathan V. Last reviews Bryan Caplan's Selfish Reasons to Have More Kids in the WSJ:
In study after study, researchers find that parents are consistently less happy than non-parents. ... Mr. Caplan bravely acknowledges this problem but is never able to say clearly what, exactly, the benefits of parenthood really are. Kids, he says, are "ridiculously cute" and "playful," and "they look like you." And in any case, everyone loves grandchildren. Maybe. Maybe not. Your mileage may vary.
It would be better for all of us if Americans had more children than they currently do. (The average college- educated woman today has just 1.7 babies over the course of her life, which is not enough to sustain America's population in the long run.) But the fundamental challenge for natalists of any stripe is building a convincing rationale for why otherwise contented adults should atomize their lives to bring children into the world. And here "Selfish Reasons to Have More Kids" falters. The best argument for children isn't that they will make you happy or your life fun but that parenthood provides purpose for a well-lived life. Selfishness, in the end, is not sufficient.