In the next 50 years, Europe's population will relive - in slow motion - that plague demography, losing about a fifth of its population by 2050 and more as the decades roll on." Pretty static thinking. Would someone in 1950 have suspected that our increasing affluence would result in us having smaller families? That certainly wasn't the paradigm back in FDR's day...
No kidding. My husband and I have had more kids than we would if we were making less.
Doesn't make much sense, does it? As a generalization, at least.
For any individual adult from a purely economic point-of-view, more kids makes less sense in our current economic/governmental system. It's a sort of Prisoner's Dilemma where more kids in general helps everyone with more people paying into Social Security, etc. However, any one individual makes out like a bandit if he gets all the benefits without the cost of bringing up a bundle or two of joy.
The only reasons to have children are primarily non-economic ones that are inspired by individuals' personalities and values. I believe that over time those people who don't want to have babies will be pushed out by those who happen to want to have babies. At the point when everyone thinks that the world population is about to plunge off a cliff, a new baby boom will arise from the remaining souls who were the offspring of those "idiots" who just decided they wanted to have some kids to take care of.