The paper proposes an analysis of three perspectives on social knowledge: the social philosophy, the social sciences and the philosophy of social sciences. Starting from the Socratic idea that Philosophy is concerned about people's problems, the inquiry explores the social philosophy as a form of social knowledge and social communication. In this respect, the philosophical themes are considered a network of fundamental problems which structures a community through values, norms and common beliefs. The social is object as well as subject of philosophy. Beginning with the 19th century - when social sciences are constituted - the social also becomes research object for these sciences. Investigating society as a study object, the social sciences have claimed a positivist attitude, insisting upon the objectivity of the description of the social facts and their explanation by scientific laws, in order to make the undergoing of social phenomena intelligible. However, society is a reality that is lived and understood from inside, such that social philosophy maintains its relevance as a form of problematizing. A significant difference can be identified at the level of problematization modality: sciences are expected to offer an answer to the questions asked, whereas philosophy teaches us to ask questions and relish the problematizing attitude. The philosophical rationality also approaches its problems from the perspective of ideas, values and ideal norms, and what according to the principles of reason appears as a rightful (de jure) order cannot be brought back to the research of what exists, as de facto order. The origin of philosophical ideas lies in the communicative rationality which is historically, socially and culturally grounded.. It is from this perspective that the relevance of the social sciences' philosophy has to be also considered; this is usually described as an epistemological approach, a research about science, of the same nature as the epistemology of natural sciences, but as a matter of fact it is a perspective of acquiring the knowledge of the social and criticizing the assumptions of the social sciences from the perspective of this reflexive knowledge.