This paper contributes to the study of responsibility as a social fact (Durkheim), combining research from social psychology, philosophy, and sociology. The pivotal concept is social reflection that serves to better understand how responsibility is performed in different social situations. The paper presents an experiment, providing evidence for, inter alia, the central complexity hypothesis: Under a complex perspective (implying increased social reflection) more responsibility is performed than under a less complex perspective (implying less social reflection). The paper concludes with considerations (...) on the principle and unity of responsibility. (shrink)