In his criticism of my book Člověk a pravidla [Man and rules], Michal Ivan scrutinized my notion of implicit rule, concluding that it is flawed. In this contribution, I defend my approach, explaining the notion in greater detail. I state that my talk about the existence of an implicit rule refers to the social setting in which some kinds of social (especially linguistic) actions are governed by normative attitudes of the members of the society. These normative attitudes institute the propriety which make instances of actions of the kinds either correct or incorrect; hence people can follow or violate the rule, the rule can come into being, develop, and fade away – without it being explicitly articulated.