As health social movements (HSMs) and complementary and alternative medicine (CAM) professions increasingly mount challenges to the authority of medical knowledge, the tendency for the medical research community and medical profession to dismiss such epistemic challenges (termed here 'paternalistic progressivism') and the corresponding response from challengers that medicine is corrupt (termed here 'medical devolution') has given way to a process of incorporation of challenges under the rubric of evidence-based research (termed here the epistemic dimension of 'medical modernisation'). Under conditions of medical modernisation the distinction between lay/alternative knowledge and scientific knowledge, upon which the epistemic authority of medicine rested, is submerged in a more complex field of competing scientific networks and research programmes. Furthermore, the older policy of transmitting science to an illiterate public and suppressing dissidents is replaced by an emerging system of the 'public shaping of science', in which there is both greater agency of social movement/lay advocacy organisations and greater recognition of the legitimacy of that agency. Indirect and direct forms of the public shaping of science are discussed, as are emergent problems of co-optation. Understanding the emergent epistemic politics that are characterised here as medical modernisation requires an ongoing theoretical integration of medical sociology and the sociology of science.