Theories, scientific
Authors: Suppe Frederick 
Published: September 2018

The term ‘theory’ is used variously in science to refer to an unproven hunch, a scientific field (as in ‘electromagnetic theory’), and a conceptual device for systematically characterizing the state-transition behaviour of systems. Philosophers of science have tended to view the latter as the most fundamental, and most analyses of theories focus on it.
The Einsteinian revolution involved the rejection of the chemical ether on experimental grounds. It thus prompted philosophers and scientists to examine closely the nature of scientific theories and their connections to observation. Many sought normative analyses that precluded the introduction of ‘fictitious’ theoretical entities such as the ether. Such analyses amounted to criteria for demarcating scientific or cognitively significant claims from unscientific or metaphysical claims.
Logical positivism sought to develop an ideal language for science that would guarantee cognitive significance. The language was symbolic logic with the nonlogical vocabulary bifurcated into observational and theoretical subvocabularies. Observation terms directly designated observable entities and attributes, and the truth of statements using them was unproblematic. To prevent postulation of fictitious unobservable entities, theoretical terms were allowed only in the context of a theory which guaranteed the cognitive significance of theoretical assertions. Theories were required to contain correspondence rules that interpret theoretical terms by coordinating them in some way with observational conditions.
In the 1960s this ‘received view’ was attacked on grounds that the observational–theoretical distinction was untenable; that the correspondence rules were a heterogeneous confusion of meaning relationships, experimental design, measurement and causal relationships; that the notion of partial interpretation associated with more liberal requirements on correspondence rules was incoherent; that theories are not axiomatic systems; that symbolic logic is an inappropriate formalism; and that theories are not linguistic entities.
Alternative analyses of theories were suggested – construing theories as answers to scientific problems or as paradigms or conceptual frameworks. Gradually analyses that construe theories as extra-linguistic set-theoretic structures came to dominate post-positivistic thought. The semantic conception identifies theories with abstract theory structures like configurated state spaces that stand in mapping relations to phenomena and are the referents of linguistic theory formulations. Depending on the sort of mapping relationship required for theoretical adequacy, realist, quasi-realist or antirealist versions are obtained. Correspondence rules are avoided and some versions eschew observational–nonobservational distinctions altogether. Development of the semantic conception has tended to focus on the mediation of theories and phenomena via observation or experiment, the relations between models and theories, confirmation of theories, their ontological commitments, and semantic relations between theories, phenomena and linguistic formulations. The structuralist approach also analyses theories set-theoretically as comprised of a theory structure and a set of intended applications, but is neopositivistic in spirit and in its reliance on a relativized theoretical–nontheoretical term distinction. It has been used to explore theoreticity, the dynamics of theories as they undergo development, and incommensurability notions.
One’s analysis of theories tends to influence strongly the position one takes on issues such as such as observation, confirmation and testing, and realism versus instrumentalism versus antirealism.