An Axiomatic Model of Unbounded Utility Functions

Savage's theory of qualitative personal probabilities leads to a representation of preferences by bounded utility functions. It is possible to relieve boundedness by relaxing the too strong hypothesis of a complete ordering among the decisions. Such an attempt has already been made for objective probabilities. This paper presents an axiomatic model of decision, inspired by Savage's point of view, which enables one to include in the theory unbounded utility functions, frequently used in concrete situations of decision.