Quiggen:

Finally, game theory is much more problematic than is commonly realised. To derive a Nash equilibrium, it is necessary to define the strategy space. In real games this is not a problem. In social, economic and political operations, however, it requires that the participants have shared understandings of the problem, accessible to the modeller. In practice this is hardly ever true, and game theoretic analyses typically proceed with an essentially arbitrary assignment of strategies to players.