A letter to the editor (scroll down) from this week's issue of The Economist:

SIR – You provided an interesting analysis of how specific market factors can indirectly influence population growth. However, your initial assumptions, of undistorted commodity markets and no environmental scarcity, led you to ignore a logical conclusion. The market needs to be directly harnessed towards the goal of stabilising population growth at a sustainable level. This could be achieved through a cap-and-trade system by issuing each adult with 1.05 of a birth permit (ie, 2.1 permits per couple to achieve the replacement fertility rate) and allowing such permits to be tradable.

Adam Drucker
Charles Darwin University
Darwin, Australia

Good grief, mate, this is one of the scariest notions I've seen in awhile. Would there be forced abortions for people not having a permit for a third child? Would people be thrown in jail for a third child if they didn't get permits?

BTW, while scrolling down you might have noticed Jeff Sachs attributing over-fishing and similar ills to overpopulation (hey, Jeff, ever heard of property rights, institutions, and the like?) and two Berkeley profs connecting nuclear weapons and terrorist cells to rapid population growth in Pakistan. In short, we see from all three letters exactly what Bryan Caplan calls the Malthusian zombie.

HT to MR for the markets in everything notion even though I shouldn't refer to such a coercive scheme as a market.