A Quantitative Approach to Proportionality

This chapter is meant to address the extent to which value-based reasoning—as involved in balancing and proportionality—may include quantitative reasoning, according to arithmetic constraints. Relying on some work on cognitive and evolutionary psychology, it is argued that processing non-symbolic approximate magnitudes is a fundamental cognitive capacity, which is deployed also when we are reasoning with goals and values. A model is developed for determining the impact of alternative choice on multiple values, assessing the utilities so produced and merging these utilities into an overall evaluation, which may be used in comparisons. The model is applied to assessing legislative choice on rights and social values, according to proportionality. Finally, it is shown how proportionality assessments may be constrained by the requirement of consistency with precedents.