When does fertility in a country become so low or so high that a government needs to intervene? This paper sheds light on this population policy question, based on a worldwide survey among demographers. We examine how professionals’ policy preferences regarding fertility levels are affected by their views on the impacts of population growth/decline and by fertility in their country of residence. The median respondent suggests intervention once fertility goes below 1.4 children or above 3.0. Three results stand out: first, demographers who are concerned about the carrying capacity of the earth are more willing to intervene than those who are less concerned. Second, the context of decision-making matters: experts living in high-fertility countries are more set on intervention than those living in low-fertility countries, but their threshold fertility level is also higher. Third, political orientation matters: right-leaning demographers are more set on government intervention than left-leaning demographers.

一个国家的生育率何时变得如此之低或如此之高以至于政府需要干预？本文基于对人口统计学家的全球调查，阐明了这一人口政策问题。我们研究了专业人士对生育水平的政策偏好如何受到他们对人口增长/下降影响的看法以及他们居住国生育率的影响。一旦生育率低于 1.4 个孩子或高于 3.0 个，受访者中位数建议进行干预。三个结果突出：第一，关心地球承载能力的人口统计学家比不那么关心的人口学家更愿意进行干预。第二，决策背景：生活在高生育率国家的专家比生活在低生育率国家的专家更愿意干预，但他们的生育门槛水平也更高。第三，政治倾向很重要：右倾人口统计学家比左倾人口统计学家更倾向于政府干预。