While different worries about population size are present in public debates, political philosophers often take population size as given. This paper is an attempt to formulate a Rawlsian liberal egalitarian approach to population size: does it make sense to speak of ‘too few’ or ‘too many’ people from the point of view of justice? It argues that, drawing on key features of liberal egalitarian theory, several clear constraints on demographic developments – to the extent that they are under our control – can be formulated. Based on these claims, we can clarify both the grounds and content of our obligations to future generations.

This article explores the shift in Rawls’ just savings principle away from an initial iteration that was indifferent to previous generational savings, to one in which past historical savings are the cornerstone of the motivation to save for future generations. Attention is given to the practical application of the revised principle in the field of the environment. The revised principle is argued to be an improvement on the initial one, because previous generations have an existence and identity that is more tangible than yet-to-be future ones.