 Imre Lakatos (1970, 1971) proposed an account of scientific method in the form of his ‘methodology of scientific research programmes’ which was a development of Popper’s approach. A scientific research program was constituted by a ‘hard core’ of propositions which were retained throughout the life of that programme together with a ‘protective belt’ which was constituted by auxiliary hypotheses that were adjusted so as to reconcile the hard core with the empirical data. The attempt on the part of the proponents of the research programme to reconcile the programme to empirical data produced a series of theories \(T_1\), \(T_2\),… \(T_n\) where, at least in some cases, \(T_{i+1}\) serves to explain some data that is anomalous for \(T_i\). Lakatos held that a research programme was ‘theoretically progressive’ insofar as each new theory predicts some novel hitherto unexpected fact. A research programme is ‘empirically progressive’ to the extent that its novel empirical content was corroborated, that is, if each new theory leads to the discovery of “some new fact” (Lakatos 1970: 118). Lakatos thus offered a new solution to the demarcation problem: a research programme was pseudoscientific to the extent that it was not theoretically progressive. Theory evaluation is construed in terms of competing research programmes: a research programme defeats a rival programme by proving more empirically progressive over the long run.