Imre Lakatos, answered from the texts and cited to the page.
The unit of appraisal in the philosophy of science is not the individual theory but the scientific research programme — a sequence of theories sharing a hard core of metaphysical commitments held immune from refutation, surrounded by a protective belt of auxiliary hypotheses adjusted under empirical pressure, governed by a negative heuristic (preserve the hard core) and a positive heuristic (the agenda for developing the protective belt).123
Programmes are evaluated as progressive when they predict novel facts that turn out to be true and as degenerating when they only save appearances through ad hoc protective-belt modifications. The methodology is the rigorous answer Popper's naive falsificationism could not provide, the Kuhnian historicism could not provide, and Feyerabend's anything-goes refused to provide.4
Science is rational across paradigm shifts because research programmes can be compared on progressive and degenerating grounds.5
Let me first roughly explain the central features of this meth~dology.~ First of all my unit of appraisal is not an isolated hypothesis (or a Westman [1g72], p. 234. In his [rg72], Feyerabend slips into a Polanyiite view: he thinks that Copernicans achieved a victory of Reason with the help of their ' Lebendigheit &s Geistes'. For my use of the technical term 'methodology' cf. chapter 3, p. 153 and chapter 2, p.Philosophical Papers Vol I - The Methodology of Scientific Research Programmes, p. 186
For instance, if a planet does not move exactly as it should, the Newtonian scientist checks his conjectures concerning atmospheric refraction, concerning propagation of light in magnetic storms, and hundreds of other conjectures which are all part of the programme. He may even invent a hitherto unknown planet and calculate its position, mass and velocity in order to explain the anomaly.Philosophical Papers Vol I - The Methodology of Scientific Research Programmes, p. 12
Popper [rg34], sections 11 and 70. I use 'metaphysical' as a technical term of naive falsificationism: a contingent proposition is 'metaphysical' if it has no 'potential falsifiers'. theses which might have saved it from apparent counterevidence - like Keplerian ellipses (positive heuristic).Philosophical Papers Vol I - The Methodology of Scientific Research Programmes, p. 55
It was the falsificationist Popper who, in order to solve these problems, elaborated better than anybody else before him the cleavage between objective knowledge (in his 'third world') and its distorted reflections in individual minds. Thus he opened up the way for my demarcation between internal and external history.Philosophical Papers Vol I - The Methodology of Scientific Research Programmes, p. 117
Is it stable? The analyst faces a problem as difficult as it is interesting. And yet it is not the same problem which is present in the natural context. Real stars are not material points, and are also subject to forces other than Newtonian attraction. 7. Saturn actually has eighteen satellites. The furthest among them is Pan, discovered in 1990 thanks to the computer analysis of the images obtained from Voyager.For and Against Method - LSE Lectures + Lakatos-Feyerabend Correspondence, p. 106
settled-as-articulated