Probabilistic sophistication and stochastic monotonicity in the Savage framework

Machina and Schmeidler [Machina, M., Schmeidler, D., 1992. A more robust definition of subjective probability. Econometrica 60, 745–780] show that probabilistic sophistication can be obtained in a Savage setting without imposing expected utility by dropping Savage's axiom P2 (sure-thing principle) and strengthening his axiom P4 (weak comparative probability). Their stronger axiom, however, embodies a degree of separability analogous to P2. In this note, we obtain probabilistic sophistication using Savage's original axiom P4 and a weaker analog of Savage's P2.