The history of debate about concepts such as magic and science in the social sciences and humanities shows us that it has been difficult to shed Enlightenment concerns about causality, rationality and reason. This chapter explores the ways in which early scholars conceptualized the relationship between science, magic and religion, and the insights generated by the efforts of the subsequent generation of anthropologists to test their theories. It then examines the increasingly prominent role that the concept of ritual came to play in studies of magic and religion, although such work continued to exhibit a marked pre-occupation with questions of rationality and causality an orientation challenged by the efficacy of ritual in healing. The chapter considers the implications of these insights for contemporary studies of health and medicine, and focuses on conceptions of cancer and its treatment as a means of teasing out the problems with notions of causality embedded in science and medicine.