The possibility of group choice: pairwise comparisons and merging functions

Preferences in Arrow’s conditions are ordinal. Here we show that when intensity of preference represented by reciprocal pairwise comparisons is considered, it is always possible to construct an Arrowian social welfare function using a two-stage social choice process. In stage 1, the individual pairwise relations are mapped into a social pairwise relation. In stage 2, the social pairwise relation is used to generate a cardinal ranking and this ranking is then used to select a particular member of the choice set.