A third conclusion, which is particularly applicable whenever the facilities for communication are short of perfect, where there is inherent uncertainty about each other's value systems or choices of strategies, and especially when an outcome must be reached by a sequence of moves or maneuvers, is that some essential part of the study of mixed-motive games is necessarily empirical. This is not to say just that it is an empirical question how people do actually perform in mixed-motive games, especially games too complicated for intellectual mastery. It is a stronger statement: that the principles relevant to successful play, the strategic principles, the propositions of a normative theory, cannot be derived by purely analytical means from a priori considerations.

DEFINE: Schelling distinguishes the empirical question of how people perform from the stronger claim that normative strategic principles themselves cannot be derived analytically.

Thomas C. Schelling, The Strategy of Conflict, loc. 366