The following was posted to sciam.com on 24 September 09:
We need a serious and wide-ranging discussion of how many people our planet should be carrying. We are at about seven billion now. Is that ideal? How about eight billion (we’re getting there fast). Is that ideal? First, we need to ask what we want to achieve, as a human race, on a continuing basis for centuries into the future (science, the arts, flourishing of human and other species, etc.). Then, plus or minus a few hundred million, how many people are needed to achieve these goals (the lower bound) and how many would be so many as to prevent these goals from being attained (the higher bound). I believe we’ve already far surpassed the higher bound, but opinions may differ. In any case, it would be useful to hear candidate numbers for an ideal human population size.
– Terence Kuch