“Qualité et quantité” des vies humaines : quel arbitrage entre croissance économique et croissance démographique ?

This article deals with the question of whether and how the value of a society may vary with its population size. Methodological procedures and empirical applications are presented to address the issue. We use for this purpose a little-known but simple and attractive social evaluation approach based on critical-level generalized utilitarianism (CLGU). CLGU says that social welfare increases with population size if and only if the new lives come with a level of individual welfare higher than that of a critical level. The implementation of CLGU poses a certain number of difficulties. Among them, there is, first, the choice of an individual welfare aggregation function and, second, the value of the critical level. This paper discusses how these difficulties can be addressed. Using these tools, the paper then illustrates how we may assess whether global social welfare has improved in the last decades following the substantial increase in global population sizes.