Consistent ... but biased

Jeffrey D. Sachs's new book "Common Wealth: Economics for a Crowded Planet" has been reviewed in the New York Times. The review end with this

In an age when we don’t need to have lots of children to work the fields, or to compensate for high infant mortality, Sachs argues that it’s both economically rational — and crucial for a future of sustainable growth — for people to reproduce at a rate close to 2.1 children per family. In his acknowledgments, Sachs thanks his three children.