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|Prehistory=Concepts predating the current appreciation of contextual appraisal include epistemological concerns about the absolute appraisal of individual theories based on their available data. Early rationalist and empiricist philosophers believed in what has been called the justificationist interpretation of absolute appraisal, which states that there can be decisive proofs and refutations of individual theories. [[CiteRef:: Laudan (1970)]]

Later, probabilist interpretations were proposed stating that one cannot decisively prove a theory, but merely objectively measure its probability relative to the available evidence. This probabilistic tradition has been common amongst philosophers of science at Cambridge, and by the logical positivist tradition in Vienna. [[Larry Laudan|Laudan]] has a good discussion on probabilism in theory appraisal. [[CiteRef::Laudan (1968a)]] Both interpretations of absolute appraisal share the opinion that theory assessment concerns an individual theory taken in isolation from other theories. For instance, the logical positivists believed that scientific theories were created by constructing logical structures for empirical data.

In contrast, the comparative interpretation contends that theory assessment does not concern individual theories considered in isolation. The shift towards the comparative interpretations of theory appraisal began with the acceptance of fallibilism in epistemology. Fallibilism is the idea that no empirical belief can ever be rationally supported or justified in a conclusive way. Determining which theory is the best available requires that extant competitors be appraised by their relative merit through a comparative appraisal process. [[CiteRef::Laudan (1981)| pp. 111-140]] [[CiteRef::Laudan (1996)| pp. 211-215]] [[CiteRef::Lakatos (1970)| pp. 10-12]]

[[Thomas Kuhn]][[CiteRef::Kuhn (1962)]] saw theories as forming interrelated groups united under the banner of what he called a '''paradigm'''. Paradigms were defined as "coherent traditions of scientific research".[[CiteRef::Kuhn (1962)| p. 10]] Appraisal was thus contextual. Scientific development alternated between periods of normal science and scientific revolutions. In normal science the paradigm guides the explanation of a widening range of phenomena. The accumulation of anomalies which resist explanation can result in a scientific revolution, in which one paradigm is replaced with another. Kuhn argued that paradigms were "incommensurable", and initially described the conversion from one to another in ways that made paradigm choice seem non-rational.[[CiteRef::Kuhn (1962)| pp. 111-135]] He later suggested that paradigm choice was comparative and involved reasoned judgment guided by epistemic values that had remained fixed over history.[[CiteRef:: Kuhn (1974)]]

Like Kuhn, [[Imre Lakatos]] saw theories as grouped into interrelated sets called '''research programs''' and saw their assessment as contextual.[[CiteRef:: Lakatos (1970)|pp. 47-67]] The theories comprising a research program were not accorded equal status. Its ''hard core'' consisted of the central tenets of the research program, and its ''protective belt'' of subsidiary theories or assumptions. Theories constituting the protective belt were modified or replaced as needed to account for new experimental findings with the goal of protecting the hard core of from falsification. He recognized that theories always face "an ocean of anomalies" but saw this as only becoming significant when a new rival theory makes a successful novel prediction.[[CiteRef::Lakatos (1971a)| pp. 111, 126-128]]