The article deals with the coordination of thinking and language, logic and grammar within transcendental idealism. The author argues that Kant’s treatment of grammar as a general form of thinking extends the boundaries of his objectivity tenet. In the project of the Critiques linguistic aspects of the synthetic acts are based on the ground of judgment rules. It presupposes that grammar is a component of synthesis of empirical notions. Grammatical rules contain preconditions of the objective significance which is a connection between a category and its corresponding word. The self-consciousness thesis which unifies all the rules for synthetic acts thereby explicates a process of following the rule through its grammar usage. However, the lack of criteria for distinguishing rigorous and unrigorous rules both in Kant’s and in the philosophy of grammar would imply a revision of their theories of meaning.