In the philosophy of science, structuralism (also known as scientific structuralism or as the structuralistic theory-concept) asserts that all aspects of reality are best understood in terms of empirical scientific constructs of entities and their relations, rather than in terms of concrete entities in themselves.

Structuralism is an active research program in the philosophy of science, which was first developed in the late 1960s and throughout the 1970s by several analytic philosophers.

As an instance of structuralism, the concept of matter should be interpreted not as an absolute property of nature in itself, but instead of how scientifically-grounded mathematical relations describe how the concept of matter interacts with other properties, whether that be in a broad sense such as the gravitational fields that mass produces or more empirically as how matter interacts with sense systems of the body to produce sensations such as weight.

Structuralism's aim is to comprise all important aspects of an empirical theory in one formal framework. The proponents of this meta-theoretic theory are Frederick Suppe, Patrick Suppes, Ronald Giere, Joseph D. Sneed, Wolfgang Stegmüller, Carlos Ulises Moulines [es], Wolfgang Balzer, John Worrall, Elie Georges Zahar, Pablo Lorenzano, Otávio Bueno, Anjan Chakravartty, Tian Yu Cao, Steven French, and Michael Redhead.

The term "structural realism" for the variation of scientific realism motivated by structuralist arguments, was coined by American philosopher Grover Maxwell [es] in 1968. In 1998, the British structural realist philosopher James Ladyman distinguished epistemic and ontic forms of structural realism.

The philosophical concept of (scientific) structuralism is related to that of epistemic structural realism (ESR). ESR, a position originally and independently held by Henri Poincaré (1902), Bertrand Russell (1927), and Rudolf Carnap (1928), was resurrected by John Worrall (1989), who proposes that there is retention of structure across theory change. Worrall, for example, argued that Fresnel's equations imply that light has a structure and that Maxwell's equations, which replaced Fresnel's, do also; both characterize light as vibrations. Fresnel postulated that the vibrations were in a mechanical medium called "ether"; Maxwell postulated that the vibrations were of electric and magnetic fields. The structure in both cases is the vibrations and it was retained when Maxwell's theories replaced Fresnel's. Because structure is retained, structural realism both (a) avoids pessimistic meta-induction and (b) does not make the success of science seem miraculous, i.e., it puts forward a no-miracles argument.

The so-called Newman problem (also Newman's problem, Newman objection, Newman's objection) refers to the critical notice of Russell's The Analysis of Matter (1927) published by Max Newman in 1928. Newman argued that the ESR claim that one can know only the abstract structure of the external world trivializes scientific knowledge. The basis of his argument is the realization that "[a]ny collection of things can be organized so as to have structure W, provided there are the right number of them", where W is an arbitrary structure.

John Worrall (2000) advocates a version of ESR augmented by the Ramsey sentence reconstruction of physical theories (a Ramsey sentence aims at rendering propositions containing non-observable theoretical terms clear by substituting them with observable terms). John Worrall and Elie Georges Zahar (2001) claim that Newman's objection applies only if a distinction between observational and theoretical terms is not made.