Contributions of Samuelson and Nash

The paper
Fishburn, Peter C. & Peter P. Wakker (1995) “The Invention of the Independence Condition for Preferences,” Management Science 41, 1130-1144
discusses the invention of the independence condition. Here is some background on the topic, assigning priorities to Nash and Samuelson.

  1. Priority of Samuelson on the general concept of separability in consumer choice.
    Savage's sure-thing principle and the independence condition of decision under risk are close relatives.
  2. Shared priority of Nash (1950) with Marschak (1950) on the axiomatization of expected utility (introducing the independence condition).
    The paper
    Bleichrodt, Han, Chen Li, Ivan Moscati, & Peter P. Wakker “Nash Was a First to Axiomatize Expected Utility”
    discusses the independent invention of the independence condition by Nash (1950), simultaneously and independently from Marschak. Here is background material to document this independent discovery.