This research aims to answer the following questions: What is the concept of social philosophy? What is the theory about the relationship between values and facts? What is its relationship with philosophy, the humanities and social sciences? To this end, the paper analyzes and discusses the critical legacy of the Frankfurt School and the contemporary philosophical contributions associated with critique of modernity in order to define this new philosophical subject. This subject is not considered social science epistemology, since it is not simply a descriptive study of scientific principles, or a philosophy of society, and it is not limited to the study of social anthropology. It is rather characterized by the process of linking between the description and interpretation, and the criterion of reality, theory and practice, from a critical perspective working to achieve the values of enlightenment.