The ex ante pareto principle

The concept of ‘pareto superiority’ plays a central role in ethics, economics, and law. Pareto superiority is sometimes taken as a relation between outcomes, and sometimes as a relation between actions—even where the outcomes of the actions are uncertain. Whether one action is classed as (ex ante) pareto superior to another depends on the prospects under the actions for each person concerned. I argue that a person’s prospects (in this context) can depend on how that person is designated. Without any constraints on acceptable designators, then, the concept of pareto superiority is ill defined and gives inconsistent results. I consider various ways of completing the definition and draw out some surprising implications.