Abstract: The foundations and origins of normativity of law have always been a key question in legal philosophy which can be newly explored from the perspective of social theory where Habermas and Foucault provide different answers. Habermas attempts to rebuild modernity with the communicative rationality, arguing that although laws are changeable, they must come from the process of discourse democracy based on the principle of moral universality. Foucault, on the other hand, denies the concepts of subject and rationality as the foundation of modern society, believing that they are all shaped by micro-power under specific circumstances, so that the normative foundation of laws are still temporary, conditioned and fluid. To some extent, their debate can be summarized as the dialogue between Universalism and Contextualism. The expected construction of Social Legal Theory from a comprehensive perspective should give consideration to the both, seeking the normative meaning of specific social practice upon a sort of normative foundation which is universal but thin.