FERTILITY RATES around the world are dropping for a variety of complex reasons (see “The Population Sink” and “Darwin’s End”). While population itself continues to increase–the United States, for instance, recently passed the 300 million mark–this is the product of waning demographic momentum. The rate of increase is slowing, and, by 2080, world population will peak somewhere in the vicinity of nine billion before contracting.

Which leads us to the next question: Is population contraction a bad thing?