In various debates about science, appeal is made to the freedom of scientific research. A rationale in favor of this freedom is rarely offered. In this paper, two major arguments are reconstructed that promise to lend support to a principle of scientific freedom. According to the epistemological argument, freedom of research is required in order to organize the collective cognitive effort we call science efficiently. According to the political argument, scientific knowledge needs to be generated in ways that are independent of the major political powers because of the important role it plays for the citizens and their capacity to form well-informed political preferences. Both arguments are examined critically in order to identify their strengths and limitations. I argue that the scientific freedom established by both rests on a number of critical preconditions, and that the arguments’ force must be weighed against competing societal interests and values in each case of their application. Appeal to a principle of scientific freedom should therefore never mark the end, but rather the beginning of a public debate about the ends and means of science.