We present and defend a view labeled “practiceism” which provides a solution to the incompatibility problems. The classic incompatibility problem is inconsistency of:1. Someone who intentionally violates the rules of a game is not playing the game.2. In many cases, players intentionally violate the rules as part of playing the game.The problem has a normative counterpart:1’. In normal cases, it is wrong for a player to intentionally violate the rules of the game.2’. In many normal cases, it is not wrong (...) for a player to intentionally violate the rules of the game.According to both formalism and informalism, the rules of the game include the formal rules of the game. Both traditional positions avoid the incompatibility problems by rejecting 1 and 1'. Practiceism rejects 2 and 2’: it maintains that the rules are the rules manifested in playing the game, not the formal rules.Practiceism presents two theses: (... (shrink)