The word theory is derived from

A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be scientific, belong to a non-scientific discipline, or no discipline at all. Depending on the context, a theory’s assertions might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings.

In modern science, the term «theory» refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with the scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction («falsify») of it. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge,^[1] in contrast to more common uses of the word «theory» that imply that something is unproven or speculative (which in formal terms is better characterized by the word hypothesis).^[2] Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures, and from scientific laws, which are descriptive accounts of the way nature behaves under certain conditions.

Theories guide the enterprise of finding facts rather than of reaching goals, and are neutral concerning alternatives among values.^[3]: 131 A theory can be a body of knowledge, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.^[4]: 46

The word theory or «in theory» is sometimes used erroneously by people to explain something which they individually did not experience or test before.^[5] In those instances, semantically, it is being substituted for another concept, a hypothesis. Instead of using the word «hypothetically», it is replaced by a phrase: «in theory». In some instances the theory’s credibility could be contested by calling it «just a theory» (implying that the idea has not even been tested).^[6] Hence, that word «theory» is very often contrasted to «practice» (from Greek praxis, πρᾶξις) a Greek term for doing, which is opposed to theory.^[6] A «classical example» of the distinction between «theoretical» and «practical» uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.^[a]

Ancient usage[edit]

The English word theory derives from a technical term in philosophy in Ancient Greek. As an everyday word, theoria, θεωρία, meant «looking at, viewing, beholding», but in more technical contexts it came to refer to contemplative or speculative understandings of natural things, such as those of natural philosophers, as opposed to more practical ways of knowing things, like that of skilled orators or artisans.^[b] English-speakers have used the word theory since at least the late 16th century.^[7] Modern uses of the word theory derive from the original definition, but have taken on new shades of meaning, still based on the idea of a theory as a thoughtful and rational explanation of the general nature of things.

Although it has more mundane meanings in Greek, the word θεωρία apparently developed special uses early in the recorded history of the Greek language. In the book From Religion to Philosophy, Francis Cornford suggests that the Orphics used the word theoria to mean «passionate sympathetic contemplation».^[8] Pythagoras changed the word to mean «the passionless contemplation of rational, unchanging truth» of mathematical knowledge, because he considered this intellectual pursuit the way to reach the highest plane of existence.^[9] Pythagoras emphasized subduing emotions and bodily desires to help the intellect function at the higher plane of theory. Thus, it was Pythagoras who gave the word theory the specific meaning that led to the classical and modern concept of a distinction between theory (as uninvolved, neutral thinking) and practice.^[10]

Aristotle’s terminology, as already mentioned, contrasts theory with praxis or practice, and this contrast exists till today. For Aristotle, both practice and theory involve thinking, but the aims are different. Theoretical contemplation considers things humans do not move or change, such as nature, so it has no human aim apart from itself and the knowledge it helps create. On the other hand, praxis involves thinking, but always with an aim to desired actions, whereby humans cause change or movement themselves for their own ends. Any human movement that involves no conscious choice and thinking could not be an example of praxis or doing.^[c]

Formality[edit]

Theories are analytical tools for understanding, explaining, and making predictions about a given subject matter. There are theories in many and varied fields of study, including the arts and sciences. A formal theory is syntactic in nature and is only meaningful when given a semantic component by applying it to some content (e.g., facts and relationships of the actual historical world as it is unfolding). Theories in various fields of study are expressed in natural language, but are always constructed in such a way that their general form is identical to a theory as it is expressed in the formal language of mathematical logic. Theories may be expressed mathematically, symbolically, or in common language, but are generally expected to follow principles of rational thought or logic.

Theory is constructed of a set of sentences that are entirely true statements about the subject under consideration. However, the truth of any one of these statements is always relative to the whole theory. Therefore, the same statement may be true with respect to one theory, and not true with respect to another. This is, in ordinary language, where statements such as «He is a terrible person» cannot be judged as true or false without reference to some interpretation of who «He» is and for that matter what a «terrible person» is under the theory.^[11]

Sometimes two theories have exactly the same explanatory power because they make the same predictions. A pair of such theories is called indistinguishable or observationally equivalent, and the choice between them reduces to convenience or philosophical preference.

The form of theories is studied formally in mathematical logic, especially in model theory. When theories are studied in mathematics, they are usually expressed in some formal language and their statements are closed under application of certain procedures called rules of inference. A special case of this, an axiomatic theory, consists of axioms (or axiom schemata) and rules of inference. A theorem is a statement that can be derived from those axioms by application of these rules of inference. Theories used in applications are abstractions of observed phenomena and the resulting theorems provide solutions to real-world problems. Obvious examples include arithmetic (abstracting concepts of number), geometry (concepts of space), and probability (concepts of randomness and likelihood).

Gödel’s incompleteness theorem shows that no consistent, recursively enumerable theory (that is, one whose theorems form a recursively enumerable set) in which the concept of natural numbers can be expressed, can include all true statements about them. As a result, some domains of knowledge cannot be formalized, accurately and completely, as mathematical theories. (Here, formalizing accurately and completely means that all true propositions—and only true propositions—are derivable within the mathematical system.) This limitation, however, in no way precludes the construction of mathematical theories that formalize large bodies of scientific knowledge.

Underdetermination[edit]

A theory is underdetermined (also called indeterminacy of data to theory) if a rival, inconsistent theory is at least as consistent with the evidence. Underdetermination is an epistemological issue about the relation of evidence to conclusions.

A theory that lacks supporting evidence is generally, more properly, referred to as a hypothesis.

Intertheoretic reduction and elimination[edit]

If a new theory better explains and predicts a phenomenon than an old theory (i.e., it has more explanatory power), we are justified in believing that the newer theory describes reality more correctly. This is called an intertheoretic reduction because the terms of the old theory can be reduced to the terms of the new one. For instance, our historical understanding about sound, «light» and heat have been reduced to wave compressions and rarefactions, electromagnetic waves, and molecular kinetic energy, respectively. These terms, which are identified with each other, are called intertheoretic identities. When an old and new theory are parallel in this way, we can conclude that the new one describes the same reality, only more completely.

When a new theory uses new terms that do not reduce to terms of an older theory, but rather replace them because they misrepresent reality, it is called an intertheoretic elimination. For instance, the obsolete scientific theory that put forward an understanding of heat transfer in terms of the movement of caloric fluid was eliminated when a theory of heat as energy replaced it. Also, the theory that phlogiston is a substance released from burning and rusting material was eliminated with the new understanding of the reactivity of oxygen.

Versus theorems[edit]

Theories are distinct from theorems. A theorem is derived deductively from axioms (basic assumptions) according to a formal system of rules, sometimes as an end in itself and sometimes as a first step toward being tested or applied in a concrete situation; theorems are said to be true in the sense that the conclusions of a theorem are logical consequences of the axioms. Theories are abstract and conceptual, and are supported or challenged by observations in the world. They are ‘rigorously tentative’, meaning that they are proposed as true and expected to satisfy careful examination to account for the possibility of faulty inference or incorrect observation. Sometimes theories are incorrect, meaning that an explicit set of observations contradicts some fundamental objection or application of the theory, but more often theories are corrected to conform to new observations, by restricting the class of phenomena the theory applies to or changing the assertions made. An example of the former is the restriction of classical mechanics to phenomena involving macroscopic length scales and particle speeds much lower than the speed of light.

The theory–practice gap[edit]

Theory is often distinguished from practice. The question of whether theoretical models of work are relevant to work itself is of interest to scholars of professions such as medicine, engineering, and law, and management.^[12]: 802

This gap between theory and practice has been framed as a knowledge transfer where there is a task of translating research knowledge to be application in practice, and ensuring that practitioners are made aware of it academics have been criticized for not attempting to transfer the knowledge they produce to practitioners.^{[12]: 804 [13]} Another framing supposes that theory and knowledge seek to understand different problems and model the world in different words (using different ontologies and epistemologies) . Another framing says that research does not produce theory that is relevant to practice.^[12]: 803

In the context of management, Van de Van and Johnson propose a form of engaged scholarship where scholars examine problems that occur in practice, in an interdisciplinary fashion, producing results that create both new practical results as well as new theoretical models, but targeting theoretical results shared in an academic fashion.^[12]: 815 They use a metaphor of «arbitrage» of ideas between disciplines, distinguishing it from collaboration.^[12]: 803

Scientific[edit]

In science, the term «theory» refers to «a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment.»^[14][15] Theories must also meet further requirements, such as the ability to make falsifiable predictions with consistent accuracy across a broad area of scientific inquiry, and production of strong evidence in favor of the theory from multiple independent sources (consilience).

The strength of a scientific theory is related to the diversity of phenomena it can explain, which is measured by its ability to make falsifiable predictions with respect to those phenomena. Theories are improved (or replaced by better theories) as more evidence is gathered, so that accuracy in prediction improves over time; this increased accuracy corresponds to an increase in scientific knowledge. Scientists use theories as a foundation to gain further scientific knowledge, as well as to accomplish goals such as inventing technology or curing diseases.

Definitions from scientific organizations[edit]

The United States National Academy of Sciences defines scientific theories as follows:

The formal scientific definition of «theory» is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics) … One of the most useful properties of scientific theories is that they can be used to make predictions about natural events or phenomena that have not yet been observed.^[16]

From the American Association for the Advancement of Science:

A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not «guesses» but reliable accounts of the real world. The theory of biological evolution is more than «just a theory.» It is as factual an explanation of the universe as the atomic theory of matter or the germ theory of disease. Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact.^[15]

The term theory is not appropriate for describing scientific models or untested, but intricate hypotheses.

Philosophical views[edit]

The logical positivists thought of scientific theories as deductive theories—that a theory’s content is based on some formal system of logic and on basic axioms. In a deductive theory, any sentence which is a logical consequence of one or more of the axioms is also a sentence of that theory.^[11] This is called the received view of theories.

In the semantic view of theories, which has largely replaced the received view,^[17][18] theories are viewed as scientific models. A model is a logical framework intended to represent reality (a «model of reality»), similar to the way that a map is a graphical model that represents the territory of a city or country. In this approach, theories are a specific category of models that fulfill the necessary criteria. (See Theories as models for further discussion.)

In physics[edit]

In physics the term theory is generally used for a mathematical framework—derived from a small set of basic postulates (usually symmetries, like equality of locations in space or in time, or identity of electrons, etc.)—which is capable of producing experimental predictions for a given category of physical systems. One good example is classical electromagnetism, which encompasses results derived from gauge symmetry (sometimes called gauge invariance) in a form of a few equations called Maxwell’s equations. The specific mathematical aspects of classical electromagnetic theory are termed «laws of electromagnetism», reflecting the level of consistent and reproducible evidence that supports them. Within electromagnetic theory generally, there are numerous hypotheses about how electromagnetism applies to specific situations. Many of these hypotheses are already considered adequately tested, with new ones always in the making and perhaps untested.

Regarding the term «theoretical»[edit]

Certain tests may be infeasible or technically difficult. As a result, theories may make predictions that have not been confirmed or proven incorrect. These predictions may be described informally as «theoretical». They can be tested later, and if they are incorrect, this may lead to revision, invalidation, or rejection of the theory.
^[19]

Mathematical[edit]

In mathematics the use of the term theory is different, necessarily so, since mathematics contains no explanations of natural phenomena, per se, even though it may help provide insight into natural systems or be inspired by them. In the general sense, a mathematical theory is a branch of or topic in mathematics, such as Set theory, Number theory, Group theory, Probability theory, Game theory, Control theory, Perturbation theory, etc., such as might be appropriate for a single textbook.

In the same sense, but more specifically, the word theory is an extensive, structured collection of theorems, organized so that the proof of each theorem only requires the theorems and axioms that preceded it (no circular proofs), occurs as early as feasible in sequence (no postponed proofs), and the whole is as succinct as possible (no redundant proofs).^[d] Ideally, the sequence in which the theorems are presented is as easy to understand as possible, although illuminating a branch of mathematics is the purpose of textbooks, rather than the mathematical theory they might be written to cover.

Philosophical[edit]

A theory can be either descriptive as in science, or prescriptive (normative) as in philosophy.^[20] The latter are those whose subject matter consists not of empirical data, but rather of ideas. At least some of the elementary theorems of a philosophical theory are statements whose truth cannot necessarily be scientifically tested through empirical observation.

A field of study is sometimes named a «theory» because its basis is some initial set of assumptions describing the field’s approach to the subject. These assumptions are the elementary theorems of the particular theory, and can be thought of as the axioms of that field. Some commonly known examples include set theory and number theory; however literary theory, critical theory, and music theory are also of the same form.

Metatheory[edit]

One form of philosophical theory is a metatheory or meta-theory. A metatheory is a theory whose subject matter is some other theory or set of theories. In other words, it is a theory about theories. Statements made in the metatheory about the theory are called metatheorems.

Political[edit]

A political theory is an ethical theory about the law and government. Often the term «political theory» refers to a general view, or specific ethic, political belief or attitude, thought about politics.

Jurisprudential[edit]

In social science, jurisprudence is the philosophical theory of law. Contemporary philosophy of law addresses problems internal to law and legal systems, and problems of law as a particular social institution.

Examples[edit]

Most of the following are scientific theories. Some are not, but rather encompass a body of knowledge or art, such as Music theory and Visual Arts Theories.

• Anthropology: Carneiro’s circumscription theory
• Astronomy: Alpher–Bethe–Gamow theory — B²FH Theory — Copernican theory — Newton’s theory of gravitation — Hubble’s law — Kepler’s laws of planetary motion Ptolemaic theory
• Biology: Cell theory — Chemiosmotic theory — Evolution — Germ theory — Symbiogenesis
• Chemistry: Molecular theory — Kinetic theory of gases — Molecular orbital theory — Valence bond theory — Transition state theory — RRKM theory — Chemical graph theory — Flory–Huggins solution theory — Marcus theory — Lewis theory (successor to Brønsted–Lowry acid–base theory) — HSAB theory — Debye–Hückel theory — Thermodynamic theory of polymer elasticity — Reptation theory — Polymer field theory — Møller–Plesset perturbation theory — density functional theory — Frontier molecular orbital theory — Polyhedral skeletal electron pair theory — Baeyer strain theory — Quantum theory of atoms in molecules — Collision theory — Ligand field theory (successor to Crystal field theory) — Variational transition-state theory — Benson group increment theory — Specific ion interaction theory
• Climatology: Climate change theory (general study of climate changes) and anthropogenic climate change (ACC)/ global warming (AGW) theories (due to human activity)
• Computer Science: Automata theory — Queueing theory
• Cosmology: Big Bang Theory — Cosmic inflation — Loop quantum gravity — Superstring theory — Supergravity — Supersymmetric theory — Multiverse theory — Holographic principle — Quantum gravity — M-theory
• Economics: Macroeconomic theory — Microeconomic theory — Law of Supply and demand
• Education: Constructivist theory — Critical pedagogy theory — Education theory — Multiple intelligence theory — Progressive education theory
• Engineering: Circuit theory — Control theory — Signal theory — Systems theory — Information theory
• Film: Film theory
• Geology: Plate tectonics
• Humanities: Critical theory
• Jurisprudence or ‘Legal theory’: Natural law — Legal positivism — Legal realism — Critical legal studies
• Law: see Jurisprudence; also Case theory
• Linguistics: X-bar theory — Government and Binding — Principles and parameters — Universal grammar
• Literature: Literary theory
• Mathematics: Approximation theory — Arakelov theory — Asymptotic theory — Bifurcation theory — Catastrophe theory — Category theory — Chaos theory — Choquet theory — Coding theory — Combinatorial game theory — Computability theory — Computational complexity theory — Deformation theory — Dimension theory — Ergodic theory — Field theory — Galois theory — Game theory — Gauge theory — Graph theory — Group theory — Hodge theory — Homology theory — Homotopy theory — Ideal theory — Intersection theory — Invariant theory — Iwasawa theory — K-theory — KK-theory — Knot theory — L-theory — Lie theory — Littlewood–Paley theory — Matrix theory — Measure theory — Model theory — Module theory — Morse theory — Nevanlinna theory — Number theory — Obstruction theory — Operator theory — Order theory — PCF theory — Perturbation theory — Potential theory — Probability theory — Ramsey theory — Rational choice theory — Representation theory — Ring theory — Set theory — Shape theory — Small cancellation theory — Spectral theory — Stability theory — Stable theory — Sturm–Liouville theory — Surgery theory — Twistor theory — Yang–Mills theory
• Music: Music theory
• Philosophy: Proof theory — Speculative reason — Theory of truth — Type theory — Value theory — Virtue theory
• Physics: Acoustic theory — Antenna theory — Atomic theory — BCS theory — Conformal field theory — Dirac hole theory — Dynamo theory — Landau theory — M-theory — Perturbation theory — Theory of relativity (successor to classical mechanics) — Gauge theory — Quantum field theory — Scattering theory — String theory — Quantum information theory
• Psychology: Theory of mind — Cognitive dissonance theory — Attachment theory — Object permanence — Poverty of stimulus — Attribution theory — Self-fulfilling prophecy — Stockholm syndrome
• Public Budgeting: Incrementalism — Zero-based budgeting
• Public Administration: Organizational theory
• Semiotics: Intertheoricity – Transferogenesis
• Sociology: Critical theory — Engaged theory — Social theory — Sociological theory – Social capital theory
• Statistics: Extreme value theory
• Theatre: Performance theory
• Visual Arts: Aesthetics — Art educational theory — Architecture — Composition — Anatomy — Color theory — Perspective — Visual perception — Geometry — Manifolds
• Other: Obsolete scientific theories

See also[edit]

Notes[edit]

References[edit]

Citations[edit]

Sources[edit]

External links[edit]

• «How science works: Even theories change», Understanding Science by the University of California Museum of Paleontology.
• What is a Theory?

English[edit]

Etymology[edit]

From Middle French théorie, from Late Latin theōria, from Ancient Greek θεωρία (theōría, “contemplation, speculation, a looking at, things looked at”), from θεωρέω (theōréō, “I look at, view, consider, examine”), from θεωρός (theōrós, “spectator”), from θέα (théa, “view”) + ὁράω (horáō, “I see, look”) [i. e. θέαν ὁράω (théan horáō, “see, look at a view; survey + genitive”)].

Pronunciation[edit]

• (Received Pronunciation, General Australian) IPA^(key): /ˈθɪə.ɹi/, /ˈθiː.ə.ɹi/, /ˈθɪɹ.i/
• (General American) IPA^(key): /ˈθɪɚ.i/, /ˈθi.ə.ɹi/

• Rhymes: -ɪəɹi, -iːəɹi

Noun[edit]

theory (countable and uncountable, plural theories)

1. A description of an event or system that is considered to be accurate.
   • 1646, Thomas Browne, Pseudodoxia Epidemica, VII.19:

     As they encrease the hatred of vice in some, so doe they enlarge the theory of wickednesse in all.

2. (sciences) A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. [from 17th c.]
   • 1843, John Stuart Mill, «»A System of Logic, Ratiocinative and Inductive, …, Bk V, Ch 7:

     In its most proper acceptation, theory means the completed result of philosophical induction from experience.

   • 1990, Tony Bennett, Outside Literature, page 139:

     Does this mean, then, that there can be no such thing as a theory of literature?

   • 2002, Duncan Steel, The Guardian, 23 May 2002:

     It was only when Einstein’s theory of relativity was published in 1915 that physicists could show that Mercury’s «anomaly» was actually because Newton’s gravitational theory was incomplete.

   • 2003, Bill Bryson, A Short History of Nearly Everything, BCA, p. 118:

     The world would need additional decades […] before the Big Bang would begin to move from interesting idea to established theory.

   • 2009, Richard Dawkins, The Greatest Show On Earth: The Evidence for Evolution, Bantam, p. 10:

     Scientists and creationists are understanding the word «theory» in two very different senses. Evolution is a theory in the same sense as the heliocentric theory. In neither case should the word «only» be used, as in «only a theory«.

   • 2012 January 1, Michael Riordan, “Tackling Infinity”, in American Scientist‎^[1], volume 100, number 1, archived from the original on 30 April 2013, page 86:

     Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the theories.

3. (uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. [from 17th c.]

   • 1998, Elizabeth Souritz, The Great History of Russian Ballet:

     Lopukhov wrote a number of books and articles on ballet theory, as well as his memoirs.

4. (mathematics) A field of study attempting to exhaustively describe a particular class of constructs. [from 18th c.]

   Knot theory classifies the mappings of a circle into 3-space.

5. A hypothesis or conjecture. [from 18th c.]

   • 1999, Wes DeMott, Vapors:

     It’s just a theory I have, and I wonder if women would agree. But don’t men say a lot about themselves when a short-skirted woman slides out of a car or chair?

   • 2003, Sean Coughlan, The Guardian, 21 Jun 2003:

     The theory is that by stripping costs to the bone, they are able to offer ludicrously low fares.

6. (countable, logic) A set of axioms together with all statements derivable from them; or, a set of statements which are deductively closed. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems). The statements may be required to all be bound (i.e., to have no free variables).

   A theory is consistent if it has a model.

7. (obsolete) Mental conception; reflection, consideration. [16th–18th c.]

Usage notes[edit]

In scientific discourse, the sense “unproven conjecture” is discouraged (with hypothesis or conjecture preferred), due to unintentional ambiguity and intentional equivocation with the sense “well-developed statement or structure”.

Synonyms[edit]

• See also Thesaurus:supposition

Meronyms[edit]

• (in logic): axioms

Holonyms[edit]

• (in logic): formal system

Derived terms[edit]

[edit]

Translations[edit]

See also[edit]

• axiom
• postulate
• proposition

References[edit]

• theory at OneLook Dictionary Search
• theory in Keywords for Today: A 21st Century Vocabulary, edited by The Keywords Project, Colin MacCabe, Holly Yanacek, 2018.
• «theory» in Raymond Williams, Keywords (revised), 1983, Fontana Press, page 316.
• “theory”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.

Anagrams[edit]

• Yother, thyreo-

The word theory has many distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion.

In science a theory is a testable model of the manner of interaction of a set of natural phenomena, capable of predicting future occurrences or observations of the same kind, and capable of being tested through experiment or otherwise verified through empirical observation. For the scientist, «theory» is not in any way an antonym of «fact». For example, it is a fact that an apple dropped on earth has been observed to fall towards the center of the planet, and the theories commonly used to describe and explain this behavior are Newton’s theory of universal gravitation (see also gravitation), and the general theory of relativity.

In common usage, the word theory is often used to signify a conjecture, an opinion, a speculation, or a hypothesis. In this usage, a theory is not necessarily based on facts; in other words, it is not required to be consistent with true descriptions of reality. True descriptions of reality are more reflectively understood as statements which would be true independently of what people think about them.

According to the United States National Academy of Sciences,

Some scientific explanations are so well established that no new evidence is likely to alter them. The explanation becomes a scientific theory. In everyday language a theory means a hunch or speculation. Not so in science. In science, the word theory refers to a comprehensive explanation of an important feature of nature that is supported by many facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena, [National Academy of Sciences (2005), «Science, Evolution, and Creationism», a [http://www.nap.edu/catalog.php?record_id=11876#toc brochure on the book of the same title] .]

Wiktionary

Etymology

The word derives from Greek polytonic|θεωρία «theoria» (Jerome), Greek «contemplation, speculation», from polytonic|θεωρός «spectator», polytonic|θέα «thea» «a view» + polytonic|ὁρᾶν «horan» «to see», literally «looking at a show». [ [http://www.indo-european.nl/cgi-bin/response.cgi?root=leiden&morpho=0&basename=%5Cdata%5Cie%5Cfrisk&first=1&sort=lattrans&text_lattrans=theoros&method_lattrans=substring&text_lemma=&method_lemma=substring&text_forms=&method_forms=substring&text_grammar=&method_grammar=substring&text_meaning=&method_meaning=substring&text_composita=&method_composita=substring&text_derivative=&method_derivative=substring&text_etymology=&method_etymology=substring&text_seealso=&method_seealso=substring&text_pages=&method_pages=substring&text_any=&method_any=substring Frisk] ; derivation from polytonic|θεός was suggested by Koller Glotta 36, 273ff.] There is a second possible etymology that traces the word back to polytonic|το θείον «to theion» «divine things» instead of «thea», reflecting the concept of contemplating the divine organisation (Cosmos) of the nature. It is attested in English since 1592. [OEtymD|theory|accessdate=2008-07-18]

cience

In scientific usage, a «theory» does not mean an unsubstantiated «guess» or «hunch», as it can in everyday speech. A theory is a logically self-consistent model or framework for describing the behavior of a related set of natural or social phenomena. It originates from or is supported by rigorous observations in the natural world, or by experimental evidence (see scientific method). In this sense, a theory is a systematic and formalized expression of all previous observations, and is predictive, logical, and testable. In principle, scientific theories are always tentative, and subject to corrections, inclusion in a yet wider theory, or succession. Commonly, many more specific hypotheses may be logically bound together by just one or two theories. As a rule for use of the term, theories tend to deal with much broader sets of universals than do hypotheses, which ordinarily deal with much more specific sets of phenomena or specific applications of a theory.

Of several competing theories, one theory may be superior to another in terms of its approximation of reality. Scientific tests of the quality of a theory include its conformity to known facts and its ability to generate hypotheses with outcomes that would predict further testable facts.

A difference in usage of the word «fact» contributes to confusion in regard to the meaning of «theory». An appreciation of the various meanings of «fact» and «knowledge» can help to clarify an understanding of the meanings of «theory». (See also: relativity of knowledge, under Relativism.)

The term «theoretical»

The term «theoretical» is sometimes informally used in lieu of «hypothetical» to describe a result which is predicted by theory but has not yet been adequately tested by observation or experiment. It is not uncommon for a theory to produce predictions which are later confirmed or proven incorrect by experiment. By inference, a prediction proved incorrect by experiment demonstrates that the hypothesis is invalid. This either means the theory is incorrect or that the experimental conjecture was wrong and the theory did not predict the hypothesis.

In physics

In physics the term «theory» is generally used for a mathematical framework—derived from a small set of basic postulates (usually symmetries—like equality of locations in space or in time, or identity of electrons, etc.)—which is capable of producing experimental predictions for a given category of physical systems. A good example is classical electromagnetism, which encompasses the results which can be derived from gauge symmetry (sometimes called gauge invariance) in a form of a few equations called Maxwell’s equations. Note that the specific theoretical aspects of classical electromagnetic theory, which have been consistently and successfully replicated for well over a century, are termed «laws of electromagnetism», reflecting the fact that they are today taken for granted. Within electromagnetic theory generally, there are numerous hypotheses about how electromagnetism applies to specific situations. Many of these hypotheses are already considered to be adequately tested, with new ones always in the making and perhaps untested.

Currently unverifiable theories

The term «theory» is regularly stretched to refer to speculation which is currently unverifiable. Examples are string theory and various theories of everything. In the strict sense, the term theory should only be used when describing a model that is derived from experimental evidence and is provable (or disprovable). It is considered sufficient for the model to be in principle testable at some undetermined point in the future.

Theories as «models»

Purpose

Theories are constructed in order to explain, predict and master phenomena (e.g. inanimate things, events, or the behaviour of animals). In many instances we are constructing models of reality. A theory makes generalizations about observations and consists of an interrelated, coherent set of ideas and models.

Description and prediction

According to Stephen Hawking in «A Brief History of Time», «a theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model which contains only a few arbitrary elements, and it must make definite predictions about the results of future observations». He goes on to state, «any physical theory is always provisional, in the sense that it is only a hypothesis; you can never prove it. No matter how many times the results of experiments agree with some theory, you can never be sure that the next time the result will not contradict the theory. On the other hand, you can disprove a theory by finding even a single observation which disagrees with the predictions of the theory». The «unprovable but falsifiable» nature of theories is a consequence of the necessity of using inductive logic.

Assumptions to formulate a theory

This is a view shared by Isaac Asimov. In «Understanding Physics», Asimov spoke of theories as «arguments» where one deduces a «scheme» or model. Arguments or theories always begin with some premises—»arbitrary elements» as Hawking calls them (see above)—which are here described as «assumptions». An assumption according to Asimov is

something accepted without proof, and it is incorrect to speak of an assumption as either true or false, since there is no way of proving it to be either (If there were, it would no longer be an assumption). It is better to consider assumptions as either useful or useless, depending on whether deductions made from them corresponded to reality. … On the other hand, it seems obvious that assumptions are the weak points in any argument, as they have to be accepted on faith in a philosophy of science that prides itself on its rationalism. Since we must start somewhere, we must have assumptions, but at least let us have as few assumptions as possible.

(See Occam’s Razor)

Example: Special Theory of Relativity

As an example of the use of assumptions to formulate a theory, consider how Albert Einstein put forth his Special Theory of Relativity. He took two phenomena which had been observed — that the «addition of velocities» is valid (Galilean transformation), and that light did not appear to have an «addition of velocities» (Michelson-Morley experiment). He assumed both observations to be correct, and formulated his theory, based on these assumptions, by simply altering the Galilean transformation to accommodate the lack of addition of velocities with regard to the speed of light. The model created in his theory is, therefore, based on the assumption that light maintains a constant velocity (or more commonly: the speed of light is a constant).

Example: Ptolemy

An example of how theories are models can be seen from theories on the planetary system. The Greeks formulated theories which were recorded by the astronomer Ptolemy. In Ptolemy’s planetary model, the earth was at the center, the planets and the sun made circular orbits around the earth, and the stars were on a sphere outside of the orbits of the planet and the earth. Retrograde motion of the planets was explained by smaller circular orbits of individual planets. This could be illustrated as a model, and could even be built into a literal model. Mathematical calculations could be made which predicted, to a great degree of accuracy, where the planets would be. His model of the planetary system survived for over 1500 years until the time of Copernicus. So one can see that a theory is a «model of reality,» one which explains certain scientific facts; yet the theory may not be a satisfactory picture of reality. Another, more acceptable, theory can later replace the previous model, as when the Copernican theory replaced the Ptolemaic theory. Or a new theory can be used to modify an older theory as when Einstein modified Newtonian mechanics (which is still used for designing bridges and gasoline engines) with his theories of relativity.

Differences between theory and model

Central to the nature of models, from general models to scale models, is the employment of representation (literally, «re-presentation») to describe particular aspects of a phenomenon or the manner of interaction among a set of phenomena. For instance, a scale model of a house or of a solar system is clearly not an actual house or an actual solar system; the aspects of an actual house or an actual solar system represented in a scale model are, only in certain limited ways, representative of the actual entity. In most ways that matter, the scale model of a house is not a house. Several commentators (e.g., Reese & Overton 1970; Lerner, 1998; Lerner & Teti, 2005, in the context of modeling human behavior) have stated that the important difference between theories and models is that the first is explanatory as well as descriptive, while the second is only descriptive (although still predictive in a more limited sense). General models and theories, according to philosopher Stephen Pepper (1948)—who also distinguishes between theories and models—are predicated on a «root» metaphor which constrains how scientists theorize and model a phenomenon and thus arrive at testable hypotheses.

In engineering practice, a distinction is made between «mathematical models» and «physical models».

Characteristics

The difference between science and unscientific nonsense was well caught in Wolfgang Pauli’s famous comment on a paper he was shown: «This isn’t right. It’s not even wrong.»

Essential criteria

The defining characteristic of a scientific theory is that it makes falsifiable or testable predictions. The relevance, and specificity of those predictions determine how (potentially) useful the theory is. A would-be theory which makes no predictions which can be observed is not a useful theory. Predictions which are not sufficiently specific to be tested are similarly not useful. In both cases, the term «theory» is inapplicable.

In practice a body of descriptions of knowledge is usually only called a theory once it has a minimum empirical basis. That is, it:
* is consistent with pre-existing theory to the extent that the pre-existing theory was experimentally verified, though it will often show pre-existing theory to be wrong in an exact sense, and
* is supported by many strands of evidence rather than a single foundation, ensuring that it is probably a good approximation, if not totally correct.

Non-essential criteria

Additionally, a theory is generally only taken seriously if it:
* is tentative, correctable and dynamic, in allowing for changes to be made as new data are discovered, rather than asserting certainty, and
* is the most parsimonious explanation, sparing in proposed entities or explanations, commonly referred to as passing the Occam’s razor test.

This is true of such established theories as special and general relativity, quantum mechanics, plate tectonics, evolution, etc. Theories considered scientific meet at least most, but ideally all, of these extra criteria.

Theories do not have to be perfectly accurate to be scientifically useful. The predictions made by Classical mechanics are known to be inaccurate, but they are sufficiently good approximations in most circumstances that they are still very useful and widely used in place of more accurate but mathematically difficult theories.

Indistinguishable theories

Sometimes it happens that two theories are found to make exactly the same predictions. In this case, they are indistinguishable, and the choice between them reduces to which is the more convenient or philosophical preference.

Criterion for scientific status

Karl Popper described the characteristics of a scientific theory as follows:

# It is easy to obtain confirmations, or verifications, for nearly every theory—if we look for confirmations.
# Confirmations should count only if they are the result of risky predictions; that is to say, if, unenlightened by the theory in question, we should have expected an event which was incompatible with the theory—an event which would have refuted the theory.
# Every «good» scientific theory is a prohibition: it forbids certain things to happen. The more a theory forbids, the better it is.
# A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory (as people often think) but a vice.
# Every genuine test of a theory is an attempt to falsify it, or to refute it. Testability is falsifiability; but there are degrees of testability: some theories are more testable, more exposed to refutation, than others; they take, as it were, greater risks.
# Confirming evidence should not count except when it is the result of a genuine test of the theory; and this means that it can be presented as a serious but unsuccessful attempt to falsify the theory. (I now speak in such cases of «corroborating evidence».)
# Some genuinely testable theories, when found to be false, are still upheld by their admirers—for example by introducing ad hoc some auxiliary assumption, or by reinterpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later describe such a rescuing operation as a «conventionalist twist» or a «conventionalist stratagem».)

One can sum up all this by saying that according to Popper, the criterion of the scientific status of a theory is its falsifiability, or refutability, or testability.

Several philosophers and historians of science have, however, argued that Popper’s definition of theory as a set of falsifiable statements is wrong [Hempel. C.G. 1951 «Problems and Changes in the Empiricist Criterion of Meaning» in «Aspects of Scientific Explanation». Glencoe: the Free Press. Quine, W.V.O 1952 «Two Dogmas of Empiricism» reprinted in «From a Logical Point of View». Cambridge: Harvard University Press] because, as Philip Kitcher has pointed out, if one took a strictly Popperian view of «theory», observations of Uranus when first discovered in 1781 would have «falsified» Newton’s celestial mechanics. Rather, people suggested that another planet influenced Uranus’ orbit—and this prediction was indeed eventually confirmed. Kitcher agrees with Popper that «there is surely something right in the idea that a science can succeed only if it can fail». [Philip Kitcher 1982 «Abusing Science: The Case Against Creationism». Page 45 Cambridge: The MIT Press] He also takes into account Hempel and Quine’s critiques of Popper, to the effect that scientific theories include statements that cannot be falsified (presumably what Hawking alluded to as arbitrary elements), and the point that good theories must also be creative. He insists that we view scientific theories as consisting of an «elaborate collection of statements», some of which are not falsifiable, while others—those he calls «auxiliary hypotheses», are.

According to Kitcher, good scientific theories must have three features:
# Unity: «A science should be unified…. Good theories consist of just one problem-solving strategy, or a small family of problem-solving strategies, that can be applied to a wide range of problems» (1982: 47).
# Fecundity: «A great scientific theory, like Newton’s, opens up new areas of research…. Because a theory presents a new way of looking at the world, it can lead us to ask new questions, and so to embark on new and fruitful lines of inquiry…. Typically, a flourishing science is incomplete. At any time, it raised more questions than it can currently answer. But incompleteness is not vice. On the contrary, incompleteness is the mother of fecundity…. A good theory should be productive; it should raise new questions and presume that those questions can be answered without giving up its problem-solving strategies» (1982: 47–48).
# Auxiliary hypotheses that are independently testable: «An auxiliary hypothesis ought to be testable independently of the particular problem it is introduced to solve, independently of the theory it is designed to save» (1982: 46) (e.g. the evidence for the existence of Neptune is independent of the anomalies in Uranus’s orbit).

Like other definitions of theories, including Popper’s, Kitcher makes it clear that a good theory includes statements that have (in his terms) «observational consequences». But, like the observation of irregularities in the orbit of Uranus, falsification is only one possible consequence of observation. The production of new hypotheses is another possible—and equally important—observational consequence.

Mathematics

In mathematics, the word theory is used informally to refer to certain distinct bodies of knowledge about mathematics. This knowledge consists of axioms, definitions, theorems and computational techniques, all related in some way by tradition or practice. Examples include group theory, set theory, Lebesgue integration theory and field theory.

The term theory also has a precise technical usage in mathematics, particularly in mathematical logic and model theory. A theory in this sense is a set of statements in a formal language, which is closed under application of certain procedures called rules of inference. A special case of this, an axiomatic theory, consists of axioms (or axiom schemata) and rules of inference. A theorem is a statement which can be derived from those axioms by application of these rules of inference. Theories used in applications are abstractions of observed phenomena and the resulting theorems provide solutions to real-world problems. Obvious examples include arithmetic (abstracting concepts of number), geometry (concepts of space), and probability (concepts of randomness and likelihood).

Gödel’s incompleteness theorem shows that no consistent, recursively enumerable theory (that is, one whose theorems form a recursively enumerable set) in which the concept of natural numbers can be expressed, can include all true statements about them. As a result, some domains of knowledge cannot be formalized, accurately and completely, as mathematical theories. (Here, formalizing accurately and completely means that all true propositions—and only true propositions—are derivable within the mathematical system.) This limitation, however, in no way precludes the construction of mathematical theories which formalize large bodies of scientific knowledge.

Other fields

Theories exist not only in the so-called hard sciences, but in all fields of academic study, from philosophy to music to literature.

In the humanities, «theory» is often used as an abbreviation for critical theory or literary theory.

List of notable theories

* Astronomy: Big Bang Theory
* Biology: Cell theory — Evolution
* Chemistry: Atomic theory — Kinetic theory of gases
* Climatology: Theory of Global Climate Change (due to anthropogenic activity)
* Computer science: Algorithmic information theory — Computation theory
* Economics: Decision theory
* Education: Constructivist theory — Critical pedagogy theory — Education theory — Multiple intelligence theory — Progressive education theory
* Engineering: Circuit theory — Control theory — Signal theory — Systems theory
* Film: Film Theory
* Games: Game theory — Rational choice theory
* Geology: Plate tectonics [The theory of plate tectonics is also called the theory of continental drift.]
* Humanities: Critical theory
* Literature: Literary theory
* Mathematics: Catastrophe theory — Category theory — Chaos theory — Graph theory — Knot theory — Number theory — Probability theory — Set theory
* Music: Music theory
* Philosophy: Proof theory — Speculative reason — Theory of truth — Type theory — Value theory — Virtue theory
* Physics: Acoustic theory — Antenna theory — General relativity — Special relativity — Theory of relativity — Quantum field theory
* Planetary science: Giant impact theory
* Visual Art: Aesthetics — Art Educational theory — Architecture — Composition — Anatomy — Color theory — Perspective — Visual perception — Geometry — Manifolds
* Sociology: Sociological theory — Social theory — Critical theory
* Statistics : Extreme value theory
* Theatre : Theory relating to theatrical performance.
* Other: Obsolete scientific theories — Phlogiston theory

cientific laws

Scientific laws are similar to scientific theories in that they are principles which can be used to predict the behavior of the natural world. Both scientific laws and scientific theories are typically well-supported by observations and/or experimental evidence. Usually scientific laws refer to rules for how nature will behave under certain conditions. [See the article on Physical law, for example.] Scientific theories are more overarching explanations of how nature works and why it exhibits certain characteristics.

A common misconception is that scientific theories are rudimentary ideas that will eventually graduate into scientific laws when enough data and evidence has been accumulated. This is not true, as scientific theory and scientific law have different definitions. A theory does not change into a scientific law with the accumulation of new or better evidence. A theory will always remain a theory, a law will always remain a law. A theory will never become a law, and a law never was a theory. [ [http://www.evolution.mbdojo.com/theory.html theory ] ]

ee also

Notes

References

* Popper, Karl (1963), «Conjectures and Refutations», Routledge and Kegan Paul, London, UK, pp. 33–39. Reprinted in Theodore Schick (ed., 2000), «Readings in the Philosophy of Science», Mayfield Publishing Company, Mountain View, Calif., pp. 9–13.
* [http://science.kennesaw.edu/~rmatson/3380theory.html Chairman of Biology and Kennesaw State Ronald Matson’s webpage comparing scientific laws and theories]
* Hawking, Stephen (1996). «The Illustrated A Brief History of Time» (Updated and expanded ed.). New York: Bantam Books, p. 15.
* Mohr, Johnathon (2008). «Revelations and Implications of the Failure of Pragmatism: The Hijacking of Knowledge Creation by the Ivory Tower». New York: Ballantine Books. pp. 87–192.

A hypothesis is an assumption, an idea that is proposed for the sake of argument so that it can be tested to see if it might be true.

In the scientific method, the hypothesis is constructed before any applicable research has been done, apart from a basic background review. You ask a question, read up on what has been studied before, and then form a hypothesis.

A hypothesis is usually tentative; it’s an assumption or suggestion made strictly for the objective of being tested.

A theory, in contrast, is a principle that has been formed as an attempt to explain things that have already been substantiated by data. It is used in the names of a number of principles accepted in the scientific community, such as the Big Bang Theory. Because of the rigors of experimentation and control, it is understood to be more likely to be true than a hypothesis is.

In non-scientific use, however, hypothesis and theory are often used interchangeably to mean simply an idea, speculation, or hunch, with theory being the more common choice.

Since this casual use does away with the distinctions upheld by the scientific community, hypothesis and theory are prone to being wrongly interpreted even when they are encountered in scientific contexts—or at least, contexts that allude to scientific study without making the critical distinction that scientists employ when weighing hypotheses and theories.

The most common occurrence is when theory is interpreted—and sometimes even gleefully seized upon—to mean something having less truth value than other scientific principles. (The word law applies to principles so firmly established that they are almost never questioned, such as the law of gravity.)

This mistake is one of projection: since we use theory in general to mean something lightly speculated, then it’s implied that scientists must be talking about the same level of uncertainty when they use theory to refer to their well-tested and reasoned principles.

The distinction has come to the forefront particularly on occasions when the content of science curricula in schools has been challenged—notably, when a school board in Georgia put stickers on textbooks stating that evolution was «a theory, not a fact, regarding the origin of living things.» As Kenneth R. Miller, a cell biologist at Brown University, has said, a theory «doesn’t mean a hunch or a guess. A theory is a system of explanations that ties together a whole bunch of facts. It not only explains those facts, but predicts what you ought to find from other observations and experiments.”

While theories are never completely infallible, they form the basis of scientific reasoning because, as Miller said «to the best of our ability, we’ve tested them, and they’ve held up.»

Princeton’s WordNetRate this definition:3.2 / 10 votes

1. theorynoun

   a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena

   «theories can incorporate facts and laws and tested hypotheses»; «true in fact and theory»

2. hypothesis, possibility, theorynoun

   a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena

   «a scientific hypothesis that survives experimental testing becomes a scientific theory»; «he proposed a fresh theory of alkalis that later was accepted in chemical practices»

3. theorynoun

   a belief that can guide behavior

   «the architect has a theory that more is less»; «they killed him on the theory that dead men tell no tales»

WiktionaryRate this definition:4.2 / 9 votes

1. theorynoun

   Mental conception; reflection, consideration.

2. theorynoun

   A coherent statement or set of ideas that explains observed facts or phenomena, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc.

3. theorynoun

   The underlying principles or methods of a given technical skill, art etc., as opposed to its practice.

4. theorynoun

   A field of study attempting to exhaustively describe a particular class of constructs.

   Knot theory classifies the mappings of a circle into 3-space.

5. theorynoun

   A hypothesis or conjecture.

6. theorynoun

   A set of axioms together with all statements derivable from them. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems).

   A theory is consistent if it has a model.

Samuel Johnson’s DictionaryRate this definition:0.0 / 0 votes

1. THEORYnoun

   Speculation; not practice; scheme; plan or system yet subsisting only in the mind.

   Etymology: theorie, Fr. ϑεωρία.

   If they had been themselves to execute their own theory in this church, they would have seen being nearer at hand.
   Richard Hooker, b. v.

   In making gold, the means hitherto propounded to effect it are in the practice full of errour, and in the theory full of unsound imagination.
   Francis Bacon, Nat. Hist. №. 326.

   Practice alone divides the world into virtuous and vicious; but as to the theory and speculation of virtue and vice, mankind are much the same.
   Robert South, Sermons.

Webster DictionaryRate this definition:4.2 / 6 votes

1. Theorynoun

   a doctrine, or scheme of things, which terminates in speculation or contemplation, without a view to practice; hypothesis; speculation

2. Theorynoun

   an exposition of the general or abstract principles of any science; as, the theory of music

3. Theorynoun

   the science, as distinguished from the art; as, the theory and practice of medicine

4. Theorynoun

   the philosophical explanation of phenomena, either physical or moral; as, Lavoisier’s theory of combustion; Adam Smith’s theory of moral sentiments

FreebaseRate this definition:2.4 / 5 votes

1. Theory

   Theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context, the results might for example include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several different related meanings. A theory is not the same as a hypothesis, as a theory is a ‘proven’ hypothesis, that, in other words, has never been disproved through experiment, and has a basis in fact.
   One modern group of meanings emphasizes the speculative and generalizing nature of theory. For example in the arts and philosophy, the term «theoretical» may be used to describe ideas and empirical phenomena which are not easily measurable. And by extension of the philosophical meaning, «theoria» is also a word still used in theological contexts. As already in Aristotle’s definitions, theory is very often contrasted to «practice» a Greek term for «doing», which is opposed to theory because pure theory involves no doing apart from itself. A classical example of the distinction between theoretical and practical uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.

The New Hacker’s DictionaryRate this definition:4.0 / 1 vote

1. theory

   The consensus, idea, plan, story, or set of rules that is currently
   being used to inform a behavior. This usage is a generalization and
   (deliberate) abuse of the technical meaning. “What’s the theory on
   fixing this TECO loss?” “What’s the theory on dinner
   tonight?” (“Chinatown, I guess.”) “What’s the
   current theory on letting lusers on during the day?” “The
   theory behind this change is to fix the following well-known
   screw….”

Editors ContributionRate this definition:0.0 / 0 votes

1. theory

   A conceptual framework established for a given phenomenon.

   Theory of motivation

   Submitted by anonymous on July 24, 2019  

Matched Categories

1. • Belief
   • Explanation

British National Corpus

1. Spoken Corpus Frequency

   Rank popularity for the word ‘theory’ in Spoken Corpus Frequency: #724

2. Written Corpus Frequency

   Rank popularity for the word ‘theory’ in Written Corpus Frequency: #1839

3. Nouns Frequency

   Rank popularity for the word ‘theory’ in Nouns Frequency: #228

How to pronounce theory?

How to say theory in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of theory in Chaldean Numerology is: 6

2. Pythagorean Numerology

   The numerical value of theory in Pythagorean Numerology is: 1

Examples of theory in a Sentence

1. Rob Portman:

   Her previous support of critical race theory is deeply concerning to me and I think that’s true with a number of my colleagues.

2. John Quincy Adams:

   It is a source of gratification and of encouragement to me to observe that the great result of this experiment upon the theory of human rights has at the close of that generation by which it was formed been crowned with success equal to the most sanguine expectations of its founders.

3. Kathy McWhorter:

   Being on school boards, getting into elected offices so that you know what the curriculum is that is being taught and you can take a stand and see if you can change that curriculum and get critical race theory out of our schools.

4. Mayim Bialik:

   Being part of ‘ The Big Bang Theory ’ for gosh, almost a decade of my life, was a thrill, it was a real thrill as an actor to be employed for that long and to be employed at something that I enjoyed so much with people that I enjoyed working with so much. As a neuroscientist in real life, I really enjoyed going to a job where our intellect is appreciated and our characters ’ intellects were appreciated.

5. Scott Brown:

   We’re back to the every other day theory, bouncing around a little, but I don’t see too strong a sentiment either way.

Popularity rank by frequency of use

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Translations for theory

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• نظريةArabic
• teoriaCatalan, Valencian
• teorieCzech
• TheorieGerman
• θεωρίαGreek
• teoríaSpanish
• نظریه, تئوریPersian
• teoriaFinnish
• théorieFrench
• teoiricIrish
• beachd-smaoinScottish Gaelic
• सिद्धान्तHindi
• teoriHaitian Creole
• elméletHungarian
• teoriaItalian
• 推論, 理論, 見解, 推測, 憶測, 定理, 学説Japanese
• ទ្រឹស្ដីKhmer
• теоријаMacedonian
• teorijaMaltese
• theorieDutch
• teoriNorwegian
• teoriaPolish
• teoriaPortuguese
• teorie, teoriiRomanian
• гипотеза, теорияRussian
• tèōrija, тѐо̄ријаSerbo-Croatian
• teoriSwedish
• கோட்பாடுTamil
• సిద్ధాంతంTelugu
• نظریہUrdu
• teorod, teorVolapük
• טעאָריעYiddish
• 理論Chinese

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