Introduction

The literature on game theory covers various given games between individual players; it recommends diverse strategies (namely diverse plans of actions) for diverse games, particularly those in Nash equilibria, namely, those in which no player benefits from altering strategies while opponents stick to theirs. Surprisingly, sometimes the potential gain from moving from one Nash equilibrium to another is no incentive for players to act accordingly. The literature also covers discussions of what game to design in order to achieve a given goal. This part is the mechanism design theory. Its purpose is to serve social planners ignorant of the preferences of the people involved. The theory of games avoidance adds to game theory the game of choosing what game to play and what game to refuse to play. This comprises a shift from the maximalist position—aiming to maximize profit—to the minimalist one—aiming at minimizing loss. This raises a discussion of the question, what set of games is advisable to encourage? It is advisable to encourage playing some groups of games, such as trade, and discourages playing other groups of games, such as wars. This shift makes the theory much more applicable to social science: usually, it is impractical to choose what game to play, but it is highly practicable to choose what game not to play and what group of games to play. This requires legislation and similar means; the study of these means aims at the improvement of their use. Extended game theory adds to game theory also discussions of equilibria that rest on mistakes—including mistakes as to the choice of a game to play. Discussing the possibility to change both game and strategy renders game theory part-and-parcel of social science. Mathematical models do not suffice for this: it requires a clear distinction between describing options and explaining situations. Explanations may lead to efforts at improvement.