The social ontology covers a specific field of research. If the ontology is the discipline that deals with the nature and relations of being, social ontology is the discipline concerning the nature and existence of social objects. This summarized definition nevertheless has important implications in problematic terms. Indeed, our spontaneous ontology is an ontology of objects (Quine, 1957), that is to say that we assume that whatever we are talking about can find a correlation in the physical world. However, when we talk about social objects, such as beliefs, expectations, norms, institutions and rules, it is not clear that such a program – known as “naturalistic”, that is, reducing formulations into observable natural entities, for example, processes that take place in our brain – is applicable. From these central problems emerge a set of important and perennial issues in contemporary research, which we will attempt to further investigate. The epistemology of social sciences also covers a well-defined field. Epistemology, as a philosophical discipline, questions the conditions of an adequate knowledge of its object. Although there have been many discussions in general epistemology on how to conduct science, based on scientific criteria, or the status of the concept of causation, there have been even more discussions, in social sciences, when the specificity of research objects involve taking a consistent stance. It is obvious to those who are interested in these issues that the two areas are closely interconnected: we cannot know something about something that we don’t grant a certain mode of existence to, and conversely, before we can decide on the mode of existence of something, we have to know that it exists and how.