A long-standing challenge for welfare economics is to develop welfare criteria that can be applied to allocations with different population levels. Such a criterion is essential to resolve the optimal population problem, i.e., the tradeoff between population size and the welfare of each person...

This chapter reviews the SWFL approach to social choice. It does not attempt to be a complete and systematic survey of existing results, but to give a critical assesment of the main axioms and their role in filtering the ethically relevant information, in particular the measurability and...