A notable feature of the debate about scientific paradigms and theories in epidemiology has been the juxtaposition of scientific, social, and ethical arguments. In some articles on epidemiologic theory and scientific paradigms, ethical issues and professional values have been discussed in order to bolster or clarify the authors' scientific arguments or to point to future directions. However, the introduction of statements laden with social concerns, ethics, and values into a scientific discussion of epidemiologic theory tends to obscure the scientific issues at the heart of the debate. Analyses of professional values and ethics in epidemiology are vitally important, but they should be thorough and well balanced and clearly distinguished as considerations of ethical and social concerns. Judgments about the relative scientific merits of alternative scientific paradigms (or proposed refinements in existing paradigms) should be based upon scientific considerations.