Axiomempiricalv1
People care not just about outcomes but about the comparison
People care not just about outcomes but about the comparison between what they got and what they would have gotten had they chosen differently.
Why This Is an Axiom
This is the foundational claim of regret theory (Loomes & Sugden, 1982). It is an empirical observation about human emotional response to counterfactuals that classical utility theory does not predict. It cannot be derived from other axioms — it is a bedrock finding about how humans actually evaluate outcomes.