Happiness Research or Don't Worry, Just Have Kids
In recent years, psychologists have made great strides in happiness research. What Can Economists Learn From Happiness Research? by Frey and Stutzer is one excellent article on the topic. This research posits several points with striking implications for population ethics.
1) Income makes people happier, but not by much. Income is a very poor predictor of whether or not one person will be happier than another.
2) Events that seemingly should have a drastic, permanent impact on personal happiness actually have effects that fade relatively quickly.
3) This leads many to conclude that happiness is largely genetic. Each person's circumstances can affect happiness to a degree, but this degree is relatively limited. You can make yourself twice as rich but probably not twice as happy.
Many people believe that the world contains too many people (I like to stigmatize these people by calling them anti-humans). They argue that people impose negative externalities on each other, i.e., humans are a sort of living pollution. However, reducing the population makes no sense, if a person's level of happiness is largely an innate personality trait.
If millions of people instantly materialized (sort of a reverse rapture) so that the U.S. population doubled, many Greenpeace members would probably resent the new arrivals. Their happiness would temporarily plummet, but they would eventually get over it and find a way to be happy -- even with another 300 million Americans (the increased urban sprawl would be a boon to their fundraising!). Before too long, the Greenpeace members would be about as happy as they were before. To the newly materialized humans, however, the event would make them much happier, because they would now enjoy life on Earth. When it comes to happiness, being alive is the main thing; everything else is chump change.
For most fertile people, having more children would be their greatest contribution to human happiness. If they believe that their offspring would make overpopulation worse, they may have fewer kids. In any event, their joy is at least partially tempered by their intellectual error. They are confusing their greatest gift to humanity with a selfish act. Happiness research shows the way to guilt free reproduction. Having kids may not make you happier, but it will make your kids happier.
P.S. My mommy and daddy both have good dispositions, so when this teething stops, there is a good chance I'll get a kick out of life!