This paper challenges the notion that there are no deliberate systematic and logical theories of accounting and advances the duality theory of accounting inherent in the accounting equation as the basic accounting theory that provides the unifying taxonomy for the fundamental going concern theory and the other accounting theories applied in the conceptual framework of financial statements and accounting standards. The paper adopts the conceptual approach to show that the logical reasoning and meanings, inherent in the concepts and conventions that characterize the system of recording and analysis of accounting information, are governed by the duality theory embedded in the accounting equation.The paper shows that the accounting theory underlie the fundamental assumptions, principles, and conventions and that the conceptual framework of accounting and the standards are guided by several derivative theories such as the going concern theory, the capital maintenance theory, the revenue realization theory, the conservatism theory, and fair value theory.