Social theory tends to assume the following: human agency, experience and knowledge is structured by social structures and categories. This assumption evokes various questions: What is "social"? What turns an object to a social object? Is it impossible to account for the conditions of knowledge through a focus on the individual alone? What is the relation between the social structuring of human beings and their existence as agents who constitute their society and experience themselves as individuals? During the course we will examine several answers to these questions and others by some of the fathers of social thought in the 19^th and beginning of the 20^th century – Emile Durkheim, Karl Marx and Max Weber. Additionally, we will observe how the investigation of specific social fields, such as the scientific and artistic ones, in the writings of 20^th century thinkers – Thomas Kuhn, Pierre Bourdieu and Walter Benjamin – challenge these classical answers.