This paper analyzes the essence of the philosophical foundations of the legal language as it is used in certain theories in the legal philosophy. The purpose of the paper is to provide a full study of the legal language theory to determine its place in modern philosophical legal thought. The paper used methods of the history of philosophy, especially the method of rational reconstruction, and is based on the interpretation of the classical philosophical and legal texts (W. Waismann, J. L. Austin, H. Kelsen, H. Hart). The main result of the paper is the justification that the unity of logic and epistemology became the ground of application of the analytical method in the field of legal knowledge from the legal language point of view. The main conclusion of this paper is that the linguistic analysis of legal concepts for the justification of the legal decisions and their consequences expands the horizons of analytical legal philosophy and allows us to reveal the essence of legal reality in a new way. The paper was carried out within the framework of the Narikbayev KAZGUU University research project “Readability of Law”.