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title: "Structuralism (philosophy of science)"
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source: "https://en.wikipedia.org/wiki/Structuralism_(philosophy_of_science)"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:18:05.133111+00:00"
instance: "kb-cron"
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=== Ontic structural realism ===
While ESR claims that only the structure of reality is knowable, ontic structural realism (OSR) goes further to claim that structure is all there is. In this view, reality has no "nature" underlying its observed structure. Rather, reality is fundamentally structural, though variants of OSR disagree on precisely which aspects of structure are primitive. OSR is strongly motivated by modern physics, particularly quantum field theory, which undermines intuitive notions of identifiable objects with intrinsic properties. Some early quantum physicists held this view, including Hermann Weyl (1931), Ernst Cassirer (1936), and Arthur Eddington (1939). Recently, OSR has been called "the most fashionable ontological framework for modern physics".
Max Tegmark takes this concept even further with the mathematical universe hypothesis, which proposes that, if our universe is only a particular structure, then it is no more real than any other structure.

== Definition of structure ==

In mathematical logic, a mathematical structure is a standard concept. A mathematical structure is a set of abstract entities with relations between them. The natural numbers under arithmetic constitute a structure, with relations such as "is evenly divisible by" and "is greater than". Here the relation "is greater than" includes the element (3, 4), but not the element (4, 3). Points in space and the real numbers under Euclidean geometry are another structure, with relations such as "the distance between point P1 and point P2 is real number R1"; equivalently, the "distance" relation includes the element (P1, P2, R1). Other structures include the Riemann space of general relativity and the Hilbert space of quantum mechanics. The entities in a mathematical structure do not have any independent existence outside their participation in relations. Two descriptions of a structure are considered equivalent, and to be describing the same underlying structure, if there is a correspondence between the descriptions that preserves all relations.
Many proponents of structural realism formally or informally ascribe "properties" to the abstract objects; some argue that such properties, while they can perhaps be "shoehorned" into the formalism of relations, should instead be considered distinct from relations.

== Proposed structures ==
In quantum field theory (QFT), traditional proposals for "the most basic known structures" divide into "particle interpretations" such as ascribing reality to the Fock space of particles, and "field interpretations" such as considering the quantum wavefunction to be identical to the underlying reality. Varying interpretations of quantum mechanics provide one complication; another, perhaps minor, complication is that neither fields nor particles are completely localized in standard QFT. A third, less obvious, complication is that "unitarily inequivalent representations" are endemic in QFT; for example, the same patch of spacetime can be represented by a vacuum by an inertial observer, but as a thermal heat bath by an accelerating observer that perceives Unruh radiation, raising the difficult question of whether the vacuum structure or heat bath structure is the real structure, or whether both of these inequivalent structures are separately real. Another example, which does not require the complications of curved spacetime, is that in ferromagnetism, symmetry-breaking analysis results in inequivalent Hilbert spaces. More broadly, QFT's infinite degrees of freedom lead to inequivalent representations in the general case.
In general relativity, scholars often grant a "basic structure" status to the spacetime structure, sometimes via its metric.

== See also ==
Constructive empiricism, a rival yet related view
Semantic view of theories, a view often associated with structuralism
Structural-systematic philosophy, a particular form of structural realism

== Notes ==
^ α: Not to be confused with the distinct tradition of French (semiotic) structuralism.
^ β: So-called 'pessimistic meta-inductions' about theoretical knowledge have the following basic form: "Proposition p is widely believed by most contemporary experts, but p is like many other hypotheses that were widely believed by experts in the past and are disbelieved by most contemporary experts. We have as much reason to expect p to befall their fate as not, therefore we should at least suspend judgement about p if not actively disbelieve it."

== Citations ==

== References ==
W. Balzer, C. U. Moulines, J. D. Sneed, An Architectonic for Science: the Structuralist Approach. Reidel, Dordrecht, 1987.
C. M. Dawe, "The Structure of Genetics," PhD dissertation, University of London, 1982.
Humphreys, P., ed. (1994). Patrick Suppes: Scientific Philosopher, Vol. 2: Philosophy of Physics, Theory Structure and Measurement, and Action Theory, Synthese Library (Springer-Verlag).
J. D. Sneed, The Logical Structure of Mathematical Physics. Reidel, Dordrecht, 1971 (revised edition 1979).
Wolfgang Stegmüller, Probleme und Resultate der Wissenschafttheorie und Analytischen Philosophie: Die Entwicklung des neuen Strukturalismus seit 1973, 1986.
Frederick Suppe, ed., The Structure of Scientific Theories. Urbana: University of Illinois Press, 1977[1974].
John Worrall, "Structural Realism: the Best of Both Worlds" in: D. Papineau (ed.), The Philosophy of Science (Oxford, 1996).
T. Perrone, "Models, Theory Dislodgment, and Epistemic Non Asymptotic Enrichment", Idee, 7/2014, 211–230.

== External links ==
Stanford Encyclopedia of Philosophy: "Structuralism in Physics"
Ioannis Votsis – Structural Realism Bibliography (last updated on 29 June 2020)