Introduction Calls for enabling ‘critical thinking’ are ubiquitous in health professional education. However, there is little agreement in the literature or in practice as to what this term means and efforts to generate a universal definition have found limited traction. Moreover, the variability observed might suggest that multiplicity has value that the quest for universal definitions has failed to capture. In this study, we sought to map the multiple conceptions of critical thinking in circulation in health professional education to understand the relationships and tensions between them. Methods We used an inductive, qualitative approach to explore conceptions of critical thinking with educators from four health professions: medicine, nursing, pharmacy, and social work. Four participants from each profession participated in two individual in-depth semi-structured interviews, the latter of which induced reflection on a visual depiction of results generated from the first set of interviews. Results Three main conceptions of critical thinking were identified: biomedical, humanist, and social justice-oriented critical thinking. ‘Biomedical critical thinking’ was the dominant conception. While each conception had distinct features, the particular conceptions of critical thinking espoused by individual participants were not stable within or between interviews. Discussion Multiple conceptions of critical thinking likely offer educators the ability to express diverse beliefs about what ‘good thinking’ means in variable contexts. The findings suggest that any single definition of critical thinking in the health professions will be inherently contentious and, we argue, should be. Such debates, when made visible to educators and trainees, can be highly productive.