There has been a recent move within health professions education towards greater methodological rigor. This move springs, at least in part, from the increasing popularity of philosophy of science as a methodological concern; we are seeing now, more than ever, how philosophy can have an important and productive impact on science. Particularly within health professions education, which many have argued should be considered a social science, there is a sense that researchers must engage with the questions of philosophy. However, this has not always been the case; the methods of the natural sciences once being seen as the model for all science. This view is based on a lack of knowledge of philosophy of science. In this chapter, we explore the definition and breadth of this field, whilst emphasising the practical application of philosophy of science terms such as ‘paradigm’, ‘ontology’ and ‘epistemology’ for those conducting and interpreting health professions education research. Given that philosophy of science theories and concepts underpin inquiry and practice within many scientific disciplines, we aim to set the scene in this chapter in regard to the context in which health professions education pedagogy and research exist.