This commentary explores a traditionally supposed boundary between science and politics, with particular attention to activist scientists who engage in public communication. Work in fields like science and technology studies shows that framing this boundary in terms of epistemological rules fails. Boundaries dictating proper scientific activities are at best pragmatic, context-dependent, and fluid. Certainly, certain kinds of politics can undermine the integrity of scientific knowledge, but it is imperative to recognize that all science is political. As we see with activist climate scientists, certain scientific knowledge carries far-reaching political consequences. It is thus problematic to call for the “de-politicization” of science or science communication. A turn from epistemic to ethical concerns perhaps offers a more constructive way forward.