Changes

Drawing partially on Fleck’s ideas, physicist and historian of science [[Thomas_Kuhn|Thomas Kuhn]] published his ideas about scientific change as ''The Structure of Scientific Revolutions'' in 1962.[[CiteRef::Kuhn (1962)]] Kuhn spoke of ''scientific paradigms'', which are constellations of theoretical and metaphysical beliefs, values, methods, and instrumental techniques shared by a scientific discipline. A paradigm determines which questions are asked of the natural world by observation and experiment. Adherents to a paradigm engage in ''normal science'', which solves the puzzles needed to expand the range of natural phenomena that can be explained using the paradigm. Eventually, ''anomalies'' may be unearthed. These are phenomena that recalcitrantly resist explanation in terms of the paradigm. If anomalies persist and grow in number, practitioners seek fundamentally new approaches. If a new approach is successful at resolving salient anomalies and is deemed to hold promise for solving new puzzles, a ''scientific revolution'' may result, in which a new paradigm replaces the old. Because paradigms are holistic networks of theories, methods, and values, they are ''incommensurable'' with one another, meaning that the terms and categories of the old paradigm cannot be translated into those of the new. Adoption of a new paradigm thus appeared, especially to Kuhn’s critics, to involve a kind of non-rational leap of faith.[[CiteRef::Bird (2013)]] [[CiteRef::Kuhn (1962)]]

In his ''On Method'', published in 1975, philosopher [[Paul_Feyerabend|Paul Feyerabend]], an epistemic anarchist, launched a much more radical attack on the idea of a fixed scientific method, and on the rationality of science.[[CiteRef::Feyerabend (2010)]] On his account, science does not possess the regularities that would make a science of science and a theory of scientific change possible. Social constructivists likewise favored an historically contingent, relativist, and particularist view of science, which they supposed was incompatible with a coherent theory of scientific change.

Philosopher [[Imre_Lakatos|Irme Lakatos]], a proponent of the rationality of science and of a fixed scientific method launched a new account of scientific change with his ''Methodology of Scientific Research Programs'' in 1970.[[CiteRef::Lakatos (1970)]] Lakatos sought to challenge both Kuhn and Feyerabend. He saw interrelated scientific theories as constituting ''research programs''. Unlike Kuhn, he believed that scientific fields typically host multiple competing research programs and rejected the idea of coherent unitary paradigms. Not all theoretical constituents of a research program were assigned equal importance. The ''hard core'' of a research program consisted of those theoretical claims that were indispensable to it. Adherents to a research program attempt to explain an increasingly wide range of natural phenomena in terms of the core claims. This is the ''positive heuristic'' of the research program. The ''protective belt'' consists of those theoretical assumptions that allowed the application of the hard core to an increasing range of cases. Scientists used their ingenuity to protect the hard core by making alterations to the protective belt so as to protect the core from falsification. The protection of the hard core is a research program's ''negative heuristic''. A ''progressive'' research program is one that makes successful novel predictions. A ''degenerating'' research program is one whose predictions repeatedly fail, and whose protective belt must be altered in an arbitrary, ad hoc fashion to protect the hard core from falsification. Lakatos rejected Kuhn’s distinction between normal and revolutionary science, and supposed that a revolution occurs when scientists simply switch allegiance from a degenerating research program to a progressive one.

In his 1984 ''Science and Values'' philosopher [[Larry_Laudan|Larry Laudan]] accepted growing empirical evidence that the methods of science had changed with time.[[CiteRef::Grobler (1990)]] [[CiteRef::Laudan (1984)]] "Our views about the proper procedures for investigating the world", he wrote, "have been significantly affected by our shifting beliefs about how the world works".[[CiteRef::Laudan (1984)|p. 39]] However he did not accept Feyerabend’s anarchism, or his view that a coherent theory of scientific change was impossible. Laudan proposed a ''reticulated model'' of scientific rationality in which other theories, methods, and research aims all interact in the assessment of a theory, with all three subject to alteration or replacement in the light of the others. Like Lakatos, he supposed that scientific theories were linked into logically related groups which he called ''research traditions'', and rejected the radical holism of Kuhnian paradigms. Laudan distinguished between the ''acceptance'' of a theory by a scientific community as the best available and ''pursuit'' of a theory as holding potential. Similar ideas were adopted as part of the Barseghyan theory of scientific change.[[CiteRef::Barseghyan (2015)]]