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|Prehistory=In modern times philosophers have held a variety of views about how best to express the structure and content of scientific theories .[[CiteRef::Winther (2015)]].

The syntactical view holds that the structure of a scientific theory can be captured by an axiomatized system of sentences. It is expressed in a metamathematical language that included predicate logic, set theory, and model theory .[[CiteRef::Winther (2015)]]. In 1928 Rudolf Carnap published his ''The Logical Structure of the World'', which put forward this view, which was central to logical empiricism .[[CiteRef::Andersen and Hepburn (2015)]]. Hans Reichenbach, Otto Neurath, Carl Hempel, and Herbert Feigl were also major contributors. The logical empiricist answer to the question of the structure of scientific theories was a family of related ideas rather than a single approach .[[CiteRef::Mormann (2008)]]. The view was so widely accepted in the early twentieth century that it is sometimes referred to as the received view .[[CiteRef::Halvorson (2012)]].

The semantic view holds that the structure of a scientific theory can be expressed as a set of mathematical models, as models were defined by Alfred Tarski. It rejects the metamathematical language of the syntactic view .[[CiteRef::Halvorson (2012)]] [[CiteRef::Winther (2015)]]. Some important models in science include the bag model of quark confinement, the hard ball model of a gas, the Bohr model of the atom, the Gauss chain model of a polymer, the Lorentz model of the atmosphere, and the double helix model of DNA .[[CiteRef::Frigg (2006)]]. Major proponents of the semantic view include [[John Von Neumann]], who wrote on the subject in the thirties, [[Fredrick Suppe]], and [[Bas Van Fraassen ]].[[CiteRef::Winther (2015)]]. The semantic view emerged in the 1960’s and 1970’s and became the dominant view in subsequent decades. John Ladyman used it in his formulation of structural realism in physics. The semantic view has played a major role in the philosophy of biology and psychology in recent decades .[[CiteRef::Halvorson (2012)]].

The pragmatic view rejects a purely formal characterization of scientific theories entirely, and supposes that a theory necessarily consists of sentences, models, problems, standards, skills, practices, including such things as analogies, metaphors, and natural kinds, with its full characterization necessarily including elements that cannot be formalized .[[CiteRef::Mormann(2008)]] [[CiteRef::Winther (2015)]]. Proponents of the pragmatic view include Nancy Cartwright, Ian Hacking, Phillip Kitcher, and Helen Longino.