I’ve heard a wide variety of objections to my forthcoming book on kids.  But the thinkers I most respect usually argue that the empirical happiness research is my Achilles heel.  After all, they point out, the negative effect of kids on their parents’ subjective well-being is extremely robust.  Doesn’t this show that there aren’t any “selfish reasons to have more kids”?

To answer this question, it’s necessary to back up a bit.  Suppose, just suppose, that the empirical happiness literature found that parents were vastly happier than non-parents.  You might think this would be great news for my thesis.  But on reflection, it would ruin my whole story!

Here’s why.  My main message is that parents work too hard and sacrifice too much because they overestimate the power of nurture.  But if parents were already much happier than non-parents, the natural inference to draw would be that parents enjoy their lifestyle just the way it is.  If they’re already tickled pink, they don’t need me to show them an “easier” way to get the kids they want.

It would be equally bad news for me, though, if parents were much unhappier than non-parents.  After all, I’m just offering a bunch of marginal adjustments for parents to use to improve their lives.  If parents were miserable, people who already have kids could still use my advice to make their lives less awful.  But selfishly speaking, the only way to win the parenting game would be not to play.

If “parents are much happier than non-parents” and “parents are much unhappier than non-parents” both undermine my argument, when does it become most relevant?  Simple: My argument is most relevant if parents are slightly less happy than comparable non-parents.  Parents need to be within striking distance of happiness – unhappy enough to need help, but not so unhappy that they’re beyond help.

Empirically, this is precisely what we find in the data.  See for yourself in the GSS; each kid makes you roughly one percentage-point less likely to say you’re “very happy.”  My critics are absolutely right to insist that parents have a robust happiness deficit.  But despite its robustness, this happiness deficit is small.  That’s the kind of deficit people can plausibly reverse by modestly revising their parenting style.

Strange as it seems, then, the empirical evidence on kids and happiness doesn’t undermine my whole project.  Indeed, from the standpoint of my intellectual relevance, we’re in the sweet spot.  Parents do need some help – and their problems are mild enough to solve with a little economics and a little common sense.