The purpose of this paper is to clarify the basis of the validity of rules of game.
The traditional framework of the discussion (formalism vs. ethos theory, internalism vs. externalism, etc.) cannot answer the issue mentioned above.
The author seeks to verify whether the basis of the effectiveness of rules (the basis for rules to function as rules) is the basis of validity of the rules (the basis for the appropriateness of the content of the rules).
The author then presents a framework for discussion of positivism vs. interpretivism. This structure of discussion corresponds to the legal positivism vs. Dworkin dispute in the philosophy of law.
Positivism emphasizes norms based on facts such as written rules and customs and is effective for discussing the rationale for the effectiveness of rules.
Interpretivism, in contrast, focuses on the interpretation of rules supporting integration of the rule system and is useful for discussing the rationale for the validity of rules. An interpretive approach seeking to find the ethos (or principles) of games may identify the basis of the validity of rules.
Even if a player engages in conduct conforming to the rule of games, i.e., rational behavior to win without violating the rules, his/her actions may be criticized by those who watch. If so, the validity of the rules that are the basis for rational behavior may be questioned. The problem is the relationship between the ethos (or principles) of games and the rules.