Résumé
Assuming that in order to best achieve their goal, individuals adapt their behaviour to the game situation, this paper examines the appropriateness of the Berge behaviour rule and equilibrium as a complement to Nash. We define a Berge equilibrium and explain what it means to play in this fashion. We analyse the rationale of individuals playing in a situational manner, and establish an operational approach that describes the circumstances under which the same individual might play in one fashion versus another.