Human thinking is heterogeneous, and among its different forms, thinking in dyadic oppositions is associated with the concept of themata. Gerald Holton characterises themata as elements that lie beneath the structure and development of physical theories as well as of non-scientific thinking. Themata have different uses, such as a thematic concept, or a thematic component of the concept; a methodological (or epistemological) thema; and a propositional thema. Serge Moscovici has placed the concept of themata in the heart of his theory (...) of social representations which is based on ‘natural thinking’ and on forms of daily knowing, including common sense. In this article I shall explore some features of thematic concepts and of methodological themata in scientific theories and in common sense. More specifically, I shall refer to the significance of the methodological (or epistemological) thema the Self and Other(s) in common-sense thinking and in social practices. (shrink)