Cautious Dual-Self Expected Utility and Weak Uncertainty Aversion
While Gilboa and Schmeidler’s (1989) ambiguity aversion is foundational in decision theory, experimental evidence reveals persistent behavioral paradoxes under weak ambiguity attitudes. Method: We propose a novel axiom—“minimal ambiguity aversion”—and construct a rational decision framework termed *Prudent Dual-Self Expected Utility*, wherein robust choices emerge from evaluating subjective scenarios via two distinct selves and selecting the worst-case expected utility. Contribution: This work provides the first axiomatic characterization of minimal ambiguity aversion, yielding three strictly equivalent utility representation theorems. It identifies “dual-self modeling coupled with conservative worst-case selection” as the core mechanism. The framework unifies invariant biseparable preferences, subjective–objective rationality models, and utility representation theory, thereby extending both the axiomatic foundations and behavioral explanatory power of ambiguity-sensitive decision models.