A Single Relation Theory of Welfarist Social Evaluation

The paper develops a systematic relational theory of social welfare evaluation. It is formulated in terms of a single difference relation capturing basic well-being comparisons between social alternatives. A new Fundamental Equity condition deals with trade-offs between individuals. It provides a unified rationale for different two-person conditions and identifies deep connections between seemingly distinct approaches to social evaluation. Dependent on the extent of interpersonal comparability, Strong Pareto and Fundamental Equity characterize Simple Majority Relation, Leximin, Utilitarianism, a level-based Borda Relation, and a new class of Equitable Welfarist Relations. They yield a general impossibility given weak incomparability. The analysis covers social evaluation under uncertainty, variable populations, and preference foundations of well-being comparisons. The relational theory is more general and more unified than the prevalent theory of Social Welfare Functionals. It does not use contestable inter-profile conditions and invariance requirements.