Making people happy or making happy people? Questionnaire-experimental studies of population ethics and policy

Is a larger population of people living good lives a better population, all else equal? This question is central to population issues in social welfare, ethics, and policy. Many answers in the philosophical literature argue that if a policy choice results in the birth of additional people living good lives, these extra lives are irrelevant to any evaluation of the policy. This paper applies the questionnaire-experimental method of empirical studies of social choice to investigate participants' policy choices and social orderings with respect to population size and average well-being. In general, heterogeneous responses depended on the quantitative and qualitative properties of the question. In particular, an experimentally manipulated increase in population size caused an option to be more likely to be selected, on average. Overall, responses suggest that population size is not neutral to social welfare. Many participants, although not all, reported that a larger population of people living good lives could be strictly preferable, at small or no costs to average well-being.