Abstract: King Hui of Liang's question, "What benefit will you bring my state?", exposed the structural predicament of Legalist instrumental rationality in the Warring States period. Mencius deconstructed this utilitarian logic with "Why speak of benefit?" and rebuilt an ethical-political system centered on "benevolence and righteousness." Inner moral self-consciousness replaced external norms, grounding moral practice in itself. The extension of moral feelings turned top-down modeling into mutual interaction, generating ethical order through empathy. Economic security, education, and people-oriented thought formed a supportive institutional framework for rule by virtue. The "great man" embodied an independent spirit that resisted power with moral integrity, while popular will, as the medium of the Mandate of Heaven, reestablished the legitimacy of political authority. The three-tier structure of social division of labor, functional differentiation, and political checks and balances actualized a system of corresponding rights and responsibilities. This ethical-political paradigm not only offered an order-scheme integrating righteousness and utility during the Zhou-Qin transition, but also provides a profound intellectual resource for overcoming the alienation of instrumental rationality and rebuilding moral consensus today.