How might science and technology studies and science, technology and society studies (STS) learn from its studies of other knowledge traditions? This article explores this question by looking at Chinese medicine (CM). The latter has been under pressure from modernization and "scientization" for a century, and the dynamics of these pressures have been explored "symmetrically" within STS and related disciplines. But in this work, CM has been the "the case" and STS theory has held stable. This article uses a CM term, reasoning-as-propensity (shi, 勢), to look at contemporary practices of cancer care in a hospital in Taiwan. It describes how shi (勢) informed the design of a new decoction, Kuan Sin Yin, while also relating to the production of scientific knowledge, biomedical interventions, Buddhist practices, and the patients living with cancer themselves. Does CM’s use of shi (勢) simply confirm the essential and incompatible otherness of CM? Looked at from outside the answer seems to be yes. However, this article explores how STS might change itself—and the theory–practice division in STS—by thinking through shi (勢) in dialogue with its othered object. This opens the possibility of an STS for CM.