|As far as the overpopulation issue I think it's not so much an issue of overcrowding. I don't agree with that line of thought religiously speaking but also respectfully speaking. The best way I can explain why I feel the way I do is you can have 4-10 earthloving, environmentally friendly, children restoring the environment than 1 wasteful, destroying person. I don't know if that makes sense but for me it's not so much about the numbers as it is in treating our environment with respect and helping it to regenerate.
Since I was the one who brought this up, I'll respond. My dh, two children, and I are "earthloving" and "environmentally-friendly." We avoid driving as much as possible, use cloth diapers, do what we can to avoid excess packaging, buy what we can used, use bio-friendly cleaning products, eat organic where possible, recycle, compost, conseve on heating, water, etc. etc. And yet we still have to drive, using up precious resources and sending more into the air, despite all our efforts, we still have a large bag of garbage to throw away each week, we still have to make some concessions because occasionally we can't afford a necessity in a less earth-harming state, much of the organic food we purchase is still trucked around the country in gas-guzzling vehicles, we're not always perfect, etc. etc.
I know there are some who manage to do better than us, but it is extremely rare in a Western country like ours, especially like ours (USA). And even if someone does manage to use only sustainable resources and create no waste, how can he or she make sure that all his or her children, grandchildren, etc. continue in his or her footsteps? Most children will take their own paths.
I believe that slowing down the population growth is only one factor in saving this planet for our descendents' use, but it is one that I can personally participate in. Our two children will take my husband's and my places and no more. Some would ask why we had any at all, and I can respect that, but I still do believe that having and raising children is one of the greatest joys in life.
If you are interested in seeing how much effect just one more earthloving, environmentally-friendly person has on this planet, you might want to look at your ecological footprint:http://www.rprogress.org/programs/sustainability/ef/ecological footpring