The Duggars are interesting, to say the least. I always wanted 10 kids but have problems with infertility. Given that most Americans are too selfish to have more than one or two children, I don't think the Duggars' 18 kids are going to be a serious population threat. Regarding overpopulation, see the following: http://www.pop.org/
Also, for the people who say that the Duggars don't have time to spend with their children, many parents of only one or two children both work and send the kids to a combination of public school and day care. Since just about the only time those parents have to spend with their children is an hour or two after coming home from work and eating a quick dinner before putting the kids to bed, I'd bet a minute by minute comparison would show that the Duggars spend at least as much individual time with their kids as the average American couple does. The Duggars homeschool and, while I don't particularly care for their curriculum choice, they do take total responsibility for raising their children themselves.
Europe is dying because of small families. In France, the government is paying women to have children. If we didn't have so many immigrants in this nation, we would be losing population, too.
I thought this was supposed to be America where we have freedoms? Seems like having more than two or three children is one freedom our society has been brainwashed into believing is wrong; that children are a drain and a burden. Nobody seems to think about the contributions those children might make to society~like paying taxes and helping keep Social Security afloat or working in the nursing field and caring for the elderly, etc. I don't know who is going to take care of my generation when we get old, since no one is having kids.
Now that I've probably offended everybody, better jump down off my soapbox and go feed the few children I have....