Noah Smith: Rich nations need to find a cure for the baby bust

Should rich countries try to get their citizens to have more children? Social conservatives generally say yes. Centrists often tentatively agree, worrying that the financial burden of paying for aging populations will be intolerable for a shrinking base of young workers. Liberals often counter that more people in rich countries would just put pressure on the environment, and that population problems are better solved by higher immigration.The truth is, the right answer to this question probably