On reaching social consent

Abstract

We explore the process of reaching social consent by means of a model of group identification, in which we seek to relatively evaluate agents’ opinions on who belongs to a given group. Our main concerns are captured by two new axioms in this setting, dubbed separability and individual monotonicity. In the dichotomous setting, we show that the two axioms, combined with symmetry, characterize the family of consent rules. We also show that the result generalizes to the setting in which decisions can take any finite number of values (thus, not necessarily dichotomous) provided that the number of agents exceeds the number of possible values. In the most general setting, where the membership decision can be any value within a continuum set, we show that the same three axioms characterize a much richer family that we call the generalized consent rules. The latter rules extend the spirit underlying the consent rules to the general model, while keeping the issue of relative evaluation in focus.