A theory is a

Scientific Theory vs Law

'.

nature
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

, 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.

^{2}FH Theory — Copernican theory —

Transferogenesis

* Sociology:

"How science works: Even theories change"

''Understanding Science'' by the University of California Museum of Paleontology.

{{Authority control Abstraction Conceptual systems Inductive reasoning Ontology

rational
Rationality is the quality of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abi ...

type of abstract thinking
Abstraction in its main sense is a conceptual process wherein general rules and concepts are derived from the usage and classification of specific examples, literal ("real" or "concrete") signifiers, first principles, or other methods.
"An abstr ...

about a phenomenon
A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfried W ...

, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study
In fields such as epidemiology, social sciences, psychology and statistics, an observational study draws inferences from a sample (statistics), sample to a statistical population, population where the dependent and independent variables, independ ...

or research. Theories may be scientific
Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.
Science may be as old as the human species, and some of the earliest archeological evidence for ...

, 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
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

works. The word has its roots in ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

, but in modern use it has taken on several related meanings.
In modern science, the term "theory" refers to scientific theories
A scientific theory is an explanation of an aspect of the natural world and universe that has been repeatedly tested and corroborated in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluatio ...

, a well-confirmed type of explanation of nature
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

, made in a way consistent
In classical deductive logic, a consistent theory is one that does not lead to a logical contradiction. The lack of contradiction can be defined in either semantic or syntactic terms. The semantic definition states that a theory is consistent ...

with the scientific method
The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific m ...

, and fulfilling the criteria required by modern science
The history of science covers the development of science from ancient history, ancient times to the present. It encompasses all three major branches of science: natural science, natural, social science, social, and formal science, formal.
Sc ...

. Such theories are described in such a way that scientific tests should be able to provide empirical support for it, or empirical contradiction ("falsify
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a so ...

") of it. Scientific theories are the most reliable, rigorous, and comprehensive form of scientific knowledge, 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
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

''). Scientific theories are distinguished from hypotheses, which are individual empirically testable
Testability is a primary aspect of Science and the Scientific Method and is a property applying to an empirical hypothesis, involves two components:
#Falsifiability or defeasibility, which means that counterexamples to the hypothesis are logicall ...

conjecture
In mathematics, a conjecture is a conclusion or a proposition that is proffered on a tentative basis without proof. Some conjectures, such as the Riemann hypothesis (still a conjecture) or Fermat's Last Theorem (a conjecture until proven in 19 ...

s, and from scientific laws
Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) ...

, 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. A theory can be a body of knowledge
A body of knowledge (BOK or BoK) is the complete set of concepts, terms and activities that make up a professional domain, as defined by the relevant learned society or professional association.Oliver, G.R. (2012). ''Foundations of the Assumed Bus ...

, which may or may not be associated with particular explanatory models
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...

. To theorize is to develop this body of knowledge.
The word theory or "in theory" is sometimes used erroneously by people to explain something which they individually did not experience or test before. In those instances, semantically, it is being substituted for another concept
Concepts are defined as abstract ideas. They are understood to be the fundamental building blocks of the concept behind principles, thoughts and beliefs.
They play an important role in all aspects of cognition. As such, concepts are studied by s ...

, a hypothesis
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

. 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). Hence, that word "theory" is very often contrasted to " practice" (from Greek ''praxis
Praxis may refer to:
Philosophy and religion
* Praxis (process), the process by which a theory, lesson, or skill is enacted, practised, embodied, or realised
* Praxis model, a way of doing theology
* Praxis (Byzantine Rite), the practice of fai ...

'', πρᾶξις) a Greek term for ''doing'', which is opposed to theory.David J Pfeiffer. Scientific Theory vs Law

'.

Science Journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research.
Content
Articles in scientific journals are mostly written by active scientists such as s ...

(on medium.com). 30 January 2017 A "classical example" of the distinction between "theoretical" and "practical" uses the discipline of medicine: medical theory
Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from "basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scientif ...

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.
Ancient usage

The English word ''theory'' derives from a technical term in philosophy inAncient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

. As an everyday word, ''theoria
Christian mysticism is the tradition of mystical practices and mystical theology within Christianity which "concerns the preparation f the personfor, the consciousness of, and the effect of ..a direct and transformative presence of God" ...

'', , meant "looking at, viewing, beholding", but in more technical contexts it came to refer to contemplative
In a religious context, the practice of contemplation seeks a direct awareness of the divine which transcends the intellect, often in accordance with prayer or meditation.
Etymology
The word ''contemplation'' is derived from the Latin word '' ...

or speculative
Speculative may refer to:
In arts and entertainment
*Speculative art (disambiguation)
*Speculative fiction, which includes elements created out of human imagination, such as the science fiction and fantasy genres
**Speculative Fiction Group, a Per ...

understandings of natural things, such as those of natural philosopher
Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...

s, as opposed to more practical ways of knowing things, like that of skilled orators or artisans. English-speakers have used the word ''theory'' since at least the late 16th century. 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
Rationality is the quality of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abi ...

explanation of the general nature
Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

of things.
Although it has more mundane meanings in Greek, the word apparently developed special uses early in the recorded history of the Greek language
Greek ( el, label=Modern Greek, Ελληνικά, Elliniká, ; grc, Ἑλληνική, Hellēnikḗ) is an independent branch of the Indo-European family of languages, native to Greece, Cyprus, southern Italy (Calabria and Salento), southern Al ...

. In the book ''From Religion to Philosophy'', Francis Cornford
Francis Macdonald Cornford (27 February 1874 – 3 January 1943) was an English classical scholar and translator known for work on ancient philosophy, notably Plato, Parmenides, Thucydides, and ancient Greek religion. Frances Cornford, his w ...

suggests that the Orphics
Orphism (more rarely Orphicism; grc, Ὀρφικά, Orphiká) is the name given to a set of religious beliefs and practices originating in the ancient Greek and Hellenistic world, associated with literature ascribed to the mythical poet Orpheus ...

used the word ''theoria'' to mean "passionate sympathetic contemplation". Pythagoras
Pythagoras of Samos ( grc, Πυθαγόρας ὁ Σάμιος, Pythagóras ho Sámios, Pythagoras the Samos, Samian, or simply ; in Ionian Greek; ) was an ancient Ionians, Ionian Ancient Greek philosophy, Greek philosopher and the eponymou ...

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. 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.
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 Formality

Theories are analytical tools forunderstanding
Understanding is a psychological process related to an abstract or physical object, such as a person, situation, or message whereby one is able to use concepts to model that object.
Understanding is a relation between the knower and an object ...

, 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 linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure (constituency), ...

in nature and is only meaningful when given a semantic
Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and comput ...

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
In neuropsychology, linguistics, and philosophy of language, a natural language or ordinary language is any language that has evolved naturally in humans through use and repetition without conscious planning or premeditation. Natural languages ...

, 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
In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules.
The alphabet of a formal language consists of sy ...

of mathematical logic
Mathematical logic is the study of logic, formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory. Research in mathematical logic commonly addresses the mathematical properties of for ...

. Theories may be expressed mathematically, symbolically, or in common language, but are generally expected to follow principles of rational thought or logic
Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...

.
Theory is constructed of a set of sentences
''The Four Books of Sentences'' (''Libri Quattuor Sententiarum'') is a book of theology written by Peter Lombard in the 12th century. It is a systematic compilation of theology, written around 1150; it derives its name from the '' sententiae'' ...

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.Curry, Haskell, ''Foundations of Mathematical Logic''
Sometimes two theories have exactly the same explanatory power
Explanatory power is the ability of a hypothesis or theory to explain the subject matter effectively to which it pertains. Its opposite is ''explanatory impotence''.
In the past, various criteria or measures for explanatory power have been prop ...

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
In mathematical logic, model theory is the study of the relationship between formal theories (a collection of sentences in a formal language expressing statements about a mathematical structure), and their models (those structures in which the s ...

. 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
In the philosophy of logic, a rule of inference, inference rule or transformation rule is a logical form consisting of a function which takes premises, analyzes their syntax, and returns a conclusion (or conclusions). For example, the rule of ...

. A special case of this, an axiomatic theory, consists of axioms
An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

(or axiom schemata) and rules of inference. A theorem
In mathematics, a theorem is a statement that has been proved, or can be proved. The ''proof'' of a theorem is a logical argument that uses the inference rules of a deductive system to establish that the theorem is a logical consequence of th ...

is a statement that can be derived from those axioms by application of these rules of inference. Theories used in applications are abstraction
Abstraction in its main sense is a conceptual process wherein general rules and concepts are derived from the usage and classification of specific examples, literal ("real" or "concrete") signifiers, first principles, or other methods.
"An abstr ...

s of observed phenomena and the resulting theorems provide solutions to real-world problems. Obvious examples include arithmetic
Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers— addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th ...

(abstracting concepts of number), geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...

(concepts of space), and probability
Probability is the branch of mathematics concerning numerical descriptions of how likely an Event (probability theory), event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and ...

(concepts of randomness and likelihood).
Gödel's incompleteness theorem shows that no consistent, recursively enumerable
In computability theory, a set ''S'' of natural numbers is called computably enumerable (c.e.), recursively enumerable (r.e.), semidecidable, partially decidable, listable, provable or Turing-recognizable if:
*There is an algorithm such that the ...

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
True most commonly refers to truth, the state of being in congruence with fact or reality.
True may also refer to:
Places
* True, West Virginia, an unincorporated community in the United States
* True, Wisconsin, a town in the United States
* ...

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

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 ofevidence
Evidence for a proposition is what supports this proposition. It is usually understood as an indication that the supported proposition is true. What role evidence plays and how it is conceived varies from field to field.
In epistemology, evidenc ...

to conclusions.
A theory that lacks supporting evidence is generally, more properly, referred to as a hypothesis
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

.
Intertheoretic reduction and elimination

If a new theory better explains and predicts a phenomenon than an old theory (i.e., it has moreexplanatory power
Explanatory power is the ability of a hypothesis or theory to explain the subject matter effectively to which it pertains. Its opposite is ''explanatory impotence''.
In the past, various criteria or measures for explanatory power have been prop ...

), 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
This list catalogs well-accepted theories in science and pre-scientific natural philosophy and natural history which have since been superseded by scientific theories. Many discarded explanations were once supported by a scientific consensus, b ...

that put forward an understanding of heat transfer in terms of the movement of caloric fluid
The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in ...

was eliminated when a theory of heat as energy replaced it. Also, the theory that phlogiston
The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston () contained within combustible bodies and released during combustion. The name comes from the Ancient Greek (''burni ...

is a substance released from burning and rusting material was eliminated with the new understanding of the reactivity of oxygen.
Versus theorems

Theories are distinct fromtheorem
In mathematics, a theorem is a statement that has been proved, or can be proved. The ''proof'' of a theorem is a logical argument that uses the inference rules of a deductive system to establish that the theorem is a logical consequence of th ...

s. A ''theorem'' is derived
Derive may refer to:
* Derive (computer algebra system), a commercial system made by Texas Instruments
* ''Dérive'' (magazine), an Austrian science magazine on urbanism
*Dérive, a psychogeographical concept
See also
*
*Derivation (disambiguatio ...

deductively from axiom
An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

s (basic assumptions) according to a formal system
A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system.
A form ...

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 'rigor
Rigour (British English) or rigor (American English; see spelling differences) describes a condition of stiffness or strictness. These constraints may be environmentally imposed, such as "the rigours of famine"; logically imposed, such as ma ...

ously 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

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. 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 practictioners are made aware of it academics have been criticized for not attempting to transfer the knowledge they produce to practitioners. Another framing supposes that theory and knowledge seek to understand different problems and model the world in different words (using differentontologies
In computer science and information science, an ontology encompasses a representation, formal naming, and definition of the categories, properties, and relations between the concepts, data, and entities that substantiate one, many, or all domains ...

and epistemologies) . Another framing says that research does not produce theory that is relevant to practice.
In the context of management, Van de Van and Johnson propose a form of engaged scholarship Engaged scholarship is the integration of education with community development. Ethical participatory research in education is introduced to high school and undergraduate curricula to serve the mutual benefit of students, faculty, and the communiti ...

where scholars examine problems that occur in practice, in an interdisciplinary
Interdisciplinarity or interdisciplinary studies involves the combination of multiple academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fields like sociology, anthropology, psychology, ec ...

fashion, producing results that create both new practical results as well as new theoretical models, but targeting theoretical results shared in an academic fashion. They use a metaphor of "arbitrage" of ideas between disciplines, distinguishing it from collaboration.
Scientific

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 throughobservation
Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The ...

and experiment." Theories must also meet further requirements, such as the ability to make falsifiable
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a so ...

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
In science and history, consilience (also convergence of evidence or concordance of evidence) is the principle that evidence from independent, unrelated sources can "converge" on strong conclusions. That is, when multiple sources of evidence are ...

).
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
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book ''The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a so ...

predictions
A prediction (Latin ''præ-'', "before," and ''dicere'', "to say"), or forecast, is a statement about a future event or data. They are often, but not always, based upon experience or knowledge. There is no universal agreement about the exact ...

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

TheUnited States National Academy of Sciences
The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

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.From the

American Association for the Advancement of Science
The American Association for the Advancement of Science (AAAS) is an American international non-profit organization with the stated goals of promoting cooperation among scientists, defending scientific freedom, encouraging scientific respons ...

:
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.The term ''theory'' is not appropriate for describing

scientific models
Scientific modelling is a scientific activity, the aim of which is to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate by referencing it to existing and usually commonly accepted ...

or untested, but intricate hypotheses.
Philosophical views

Thelogical positivist
Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...

s thought of scientific theories as ''deductive theories''—that a theory's content is based on some formal system
A formal system is an abstract structure used for inferring theorems from axioms according to a set of rules. These rules, which are used for carrying out the inference of theorems from axioms, are the logical calculus of the formal system.
A form ...

of logic and on basic axioms
An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

. 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. This is called the received view of theories The received view of theories is a position in the philosophy of science that identifies a scientific theory with a set of propositions which are considered to be linguistic objects, such as axioms. Frederick Suppe describes the position of the r ...

.
In the semantic view of theories The semantic view of theories is a position in the philosophy of science that holds that a scientific theory can be identified with a collection of models. The semantic view of theories was originally proposed by Patrick Suppes in “A Comparison ...

, which has largely replaced the received view, theories are viewed as scientific models
Scientific modelling is a scientific activity, the aim of which is to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate by referencing it to existing and usually commonly accepted ...

. A model
A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure.
Models c ...

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

Inphysics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

the term ''theory'' is generally used for a mathematical framework—derived from a small set of basic postulates
An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

(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
Classical electromagnetism or classical electrodynamics is a branch of theoretical physics that studies the interactions between electric charges and currents using an extension of the classical Newtonian model; It is, therefore, a classical fie ...

, which encompasses results derived from gauge symmetry (sometimes called gauge invariance) in a form of a few equations called Maxwell's equations
Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits.
...

. 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"

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.Mathematical

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 asSet theory
Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly conce ...

, Number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic function, integer-valued functions. German mathematician Carl Friedrich Gauss (1777 ...

, Group theory
In abstract algebra, group theory studies the algebraic structures known as group (mathematics), groups.
The concept of a group is central to abstract algebra: other well-known algebraic structures, such as ring (mathematics), rings, field ...

, Probability theory
Probability theory is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expressing it through a set o ...

, Game theory
Game theory is the study of mathematical models of strategic interactions among rational agents. Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbs1 Chapter-preview links, ppvii–xi It has appli ...

, Control theory
Control theory is a field of mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a ...

, Perturbation theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middl ...

, 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). 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

A theory can be either ''descriptive'' as in science, or ''prescriptive'' (normative
Normative generally means relating to an evaluative standard. Normativity is the phenomenon in human societies of designating some actions or outcomes as good, desirable, or permissible, and others as bad, undesirable, or impermissible. A norm in ...

) as in philosophy. The latter are those whose subject matter consists not of empirical data, but rather of idea
In common usage and in philosophy, ideas are the results of thought. Also in philosophy, ideas can also be mental representational images of some object. Many philosophers have considered ideas to be a fundamental ontological category of being ...

s. At least some of the elementary theorems of a philosophical theory are statements whose truth cannot necessarily be scientifically tested through empirical observation
Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

.
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
Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly conce ...

and number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic function, integer-valued functions. German mathematician Carl Friedrich Gauss (1777 ...

; however literary theory
Literary theory is the systematic study of the nature of literature and of the methods for literary analysis. Culler 1997, p.1 Since the 19th century, literary scholarship includes literary theory and considerations of intellectual history, mo ...

, critical theory
A critical theory is any approach to social philosophy that focuses on society and culture to reveal, critique and challenge power structures. With roots in sociology and literary criticism, it argues that social problems stem more from soci ...

, and music theory
Music theory is the study of the practices and possibilities of music. ''The Oxford Companion to Music'' describes three interrelated uses of the term "music theory". The first is the "rudiments", that are needed to understand music notation (ke ...

are also of the same form.
Metatheory

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
Statement or statements may refer to: Common uses
*Statement (computer science), the smallest standalone element of an imperative programming language
*Statement (logic), declarative sentence that is either true or false
*Statement, a declarative ...

made in the metatheory about the theory are called metatheorem
In logic, a metatheorem is a statement about a formal system proven in a metalanguage. Unlike theorems proved within a given formal system, a metatheorem is proved within a metatheory, and may reference concepts that are present in the metathe ...

s.
Political

A political theory is anethical
Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong behavior".''Internet Encyclopedia of Philosophy'' The field of ethics, along with aesthetics, concerns ma ...

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

In social science,jurisprudence
Jurisprudence, or legal theory, is the theoretical study of the propriety of law. Scholars of jurisprudence seek to explain the nature of law in its most general form and they also seek to achieve a deeper understanding of legal reasoning a ...

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

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
Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of behavi ...

: Carneiro's circumscription theory
The circumscription theory is a theory of the role of warfare in state formation in political anthropology, created by anthropologist Robert Carneiro. The theory has been summarized in one sentence by Schacht: “In areas of circumscribed agricult ...

* Astronomy
Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

: Alpher–Bethe–Gamow theory — BNewton's theory of gravitation
Newton's law of universal gravitation is usually stated as that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distan ...

— Hubble's law
Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving a ...

— Kepler's laws of planetary motion Ptolemaic theory
* Cosmology
Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount (lexicographer), Thomas Blount's ''Glossographia'', and in 1731 taken up in ...

: Big Bang Theory — Cosmic inflation — Loop quantum gravity — Superstring theory
Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings.
'Superstring theory' is a shorthand for supersymmetric string t ...

— Supergravity
In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as ...

— Supersymmetric theory
In a supersymmetric theory the equations for force and the equations for matter are identical. In theoretical and mathematical physics, any theory with this property has the principle of supersymmetry (SUSY). Dozens of supersymmetric theories ...

— Multiverse theory
The multiverse is a hypothetical group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, information, and the physical laws and constants that describe them. The dif ...

— Holographic principle
The holographic principle is an axiom in string theories and a supposed property of quantum gravity that states that the description of a volume of space can be thought of as encoded on a lower-dimensional boundary to the region — such as a ...

— Quantum gravity — M-theory
M-theory is a theory in physics that unifies all consistent versions of superstring theory. Edward Witten first conjectured the existence of such a theory at a string theory conference at the University of Southern California in 1995. Witten's ...

* Biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...

: Cell theory
In biology, cell theory is a scientific theory first formulated in the mid-nineteenth century, that living organisms are made up of Cell (biology), cells, that they are the basic structural/organizational unit of all organisms, and that all cell ...

— Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

— Germ theory
* Chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

: Molecular theory
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

— Kinetic theory of gases
Kinetic (Ancient Greek: κίνησις “kinesis”, movement or to move) may refer to:
* Kinetic theory, describing a gas as particles in random motion
* Kinetic energy, the energy of an object that it possesses due to its motion
Art and enter ...

— Molecular orbital theory
In chemistry, molecular orbital theory (MO theory or MOT) is a method for describing the electronic structure of molecules using quantum mechanics. It was proposed early in the 20th century.
In molecular orbital theory, electrons in a molecule ...

— Valence bond theory — Transition state theory
In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions. The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes.
T ...

— RRKM theory The Rice–Ramsperger–Kassel–Marcus (RRKM) theory is a theory of chemical reactivity. It was developed by Rice and Ramsperger in 1927 and Kassel in 1928 (RRK theory) and generalized (into the RRKM theory) in 1952 by Marcus who took the tr ...

— Chemical graph theory — Flory–Huggins solution theory
Flory–Huggins solution theory is a lattice model of the thermodynamics of polymer solutions which takes account of the great dissimilarity in molecular sizes in adapting the usual expression for the entropy of mixing. The result is an equation ...

— Marcus theory
In theoretical chemistry, Marcus theory is a theory originally developed by Rudolph A. Marcus, starting in 1956, to explain the rates of electron transfer reactions – the rate at which an electron can move or jump from one chemical species ( ...

— Lewis theory (successor to Brønsted–Lowry acid–base theory
The Brønsted–Lowry theory (also called proton theory of acids and bases) is an acid–base reaction theory which was proposed independently by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923. The fundamental concept of this theory ...

) — HSAB theory
HSAB concept is a jargon for "hard and soft Lewis acids and bases, (Lewis) acids and bases". HSAB is widely used in chemistry for explaining stability of chemical compound, compounds, reaction mechanisms and pathways. It assigns the terms 'hard' o ...

— Debye–Hückel theory
The Debye–Hückel theory was proposed by Peter Debye and Erich Hückel as a theoretical explanation for departures from ideality in solutions of electrolytes and plasmas.
It is a linearized Poisson–Boltzmann model, which assumes an extrem ...

— Thermodynamic theory of polymer elasticity — Reptation theory
A peculiarity of thermal motion of very long linear macromolecules in ''entangled'' polymer melts or concentrated polymer solutions is reptation. Derived from the word reptile, reptation suggests the movement of entangled polymer chains as bein ...

— Polymer field theory
A polymer field theory is a statistical field theory describing the statistical behavior of a neutral or charged polymer system. It can be derived by transforming the partition function from its standard many-dimensional integral representation ov ...

— Møller–Plesset perturbation theory
Møller–Plesset perturbation theory (MP) is one of several quantum chemistry post–Hartree–Fock ab initio methods in the field of computational chemistry. It improves on the Hartree–Fock method by adding electron correlation effects by ...

— density functional theory
Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...

— Frontier molecular orbital theory In chemistry, frontier molecular orbital theory is an application of MO theory describing HOMO/LUMO interactions.
History
In 1952, Kenichi Fukui published a paper in the ''Journal of Chemical Physics'' titled "A molecular theory of reactivity i ...

— Polyhedral skeletal electron pair theory
In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by ...

— Baeyer strain theory
In organic chemistry, ring strain is a type of instability that exists when bonds in a molecule form angles that are abnormal. Strain is most commonly discussed for small rings such as cyclopropanes and cyclobutanes, whose internal angles are s ...

— Quantum theory of atoms in molecules — Collision theory
Collision theory is a principle of chemistry used to predict the rates of chemical reactions. It states that when suitable particles of the reactant hit each other with correct orientation, only a certain amount of collisions result in a percept ...

— Ligand field theory
Ligand field theory (LFT) describes the bonding, orbital arrangement, and other characteristics of coordination complexes. It represents an application of molecular orbital theory to transition metal complexes. A transition metal ion has nine valen ...

(successor to Crystal field theory Crystal field theory (CFT) describes the breaking of degeneracies of electron orbital states, usually ''d'' or ''f'' orbitals, due to a static electric field produced by a surrounding charge distribution (anion neighbors). This theory has been used ...

) — Variational transition-state theory — Benson group increment theory Benson may refer to:
Animals
*Benson (fish), largest common carp caught in Britain
Places Geography
Canada
*Rural Municipality of Benson No. 35, Saskatchewan; rural municipality
*Benson, Saskatchewan; hamlet
United Kingdom
*Benson, Oxfordshire
...

— Specific ion interaction theory
In theoretical chemistry, Specific ion Interaction Theory (SIT theory) is a theory used to estimate single-ion activity coefficients in electrolyte solutions at relatively high concentrations. It does so by taking into consideration ''interaction ...

* Climatology
Climatology (from Greek , ''klima'', "place, zone"; and , '' -logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of stud ...

: Climate change theory (general study of climate changes) and anthropogenic climate change (ACC)/ global warming
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

(AGW) theories (due to human activity)
* Economics: Macroeconomic theory
Macroeconomics (from the Greek prefix ''makro-'' meaning "large" + ''economics'') is a branch of economics dealing with performance, structure, behavior, and decision-making of an economy as a whole.
For example, using interest rates, taxes, and ...

— Microeconomic theory
Microeconomics is a branch of mainstream economics that studies the behavior of individuals and firms in making decisions regarding the allocation of scarce resources and the interactions among these individuals and firms. Microeconomics foc ...

— Law of Supply and demand
* Education: Constructivist theory
Constructivism may refer to:
Art and architecture
* Constructivism (art), an early 20th-century artistic movement that extols art as a practice for social purposes
* Constructivist architecture, an architectural movement in Russia in the 1920s a ...

— Critical pedagogy theory
Critical pedagogy is a philosophy of education and social movement that developed and applied concepts from critical theory and related traditions to the field of education and the study of culture.
It insists that issues of social justice and de ...

— Education theory
Education sciences or education theory (traditionally often called ''pedagogy'') seek to describe, understand, and prescribe education policy and practice. Education sciences include many topics, such as pedagogy, andragogy, curriculum, learning, ...

— Multiple intelligence theory
The theory of multiple intelligences proposes the differentiation of human intelligence into specific modalities of intelligence, rather than defining intelligence as a single, general ability. The theory has been criticized by mainstream psycho ...

— Progressive education theory
Progressive education, or protractivism, is a pedagogical movement that began in the late 19th century and has persisted in various forms to the present. In Europe, progressive education took the form of the New Education Movement. The term ''pro ...

* Engineering: Circuit theory
Circuit may refer to:
Science and technology
Electrical engineering
* Electrical circuit, a complete electrical network with a closed-loop giving a return path for current
** Analog circuit, uses continuous signal levels
** Balanced circui ...

— Control theory
Control theory is a field of mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a ...

— Signal theory
Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, and scientific measurements. Signal processing techniq ...

— Systems theory
Systems theory is the interdisciplinary study of systems, i.e. cohesive groups of interrelated, interdependent components that can be natural or human-made. Every system has causal boundaries, is influenced by its context, defined by its structu ...

— Information theory
Information theory is the scientific study of the quantification (science), quantification, computer data storage, storage, and telecommunication, communication of information. The field was originally established by the works of Harry Nyquist a ...

* Film: Film theory
* Geology: Plate tectonics
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

* Humanities
Humanities are academic disciplines that study aspects of human society and culture. In the Renaissance, the term contrasted with divinity and referred to what is now called classics, the main area of secular study in universities at the t ...

: Critical theory
A critical theory is any approach to social philosophy that focuses on society and culture to reveal, critique and challenge power structures. With roots in sociology and literary criticism, it argues that social problems stem more from soci ...

* Jurisprudence
Jurisprudence, or legal theory, is the theoretical study of the propriety of law. Scholars of jurisprudence seek to explain the nature of law in its most general form and they also seek to achieve a deeper understanding of legal reasoning a ...

or 'Legal theory': Natural law
Natural law ( la, ius naturale, ''lex naturalis'') is a system of law based on a close observation of human nature, and based on values intrinsic to human nature that can be deduced and applied independently of positive law (the express enacte ...

— Legal positivism
Legal positivism (as understood in the Anglosphere) is a school of thought of analytical jurisprudence developed largely by legal philosophers during the 18th and 19th centuries, such as Jeremy Bentham and John Austin. While Bentham and Austin de ...

— Legal realism
Legal realism is a naturalistic approach to law. It is the view that jurisprudence should emulate the methods of natural science, i.e., rely on empirical evidence. Hypotheses must be tested against observations of the world.
Legal realists be ...

— Critical legal studies
Critical legal studies (CLS) is a school of critical theory that developed in the United States during the 1970s.Alan Hunt, "The Theory of Critical Legal Studies," Oxford Journal of Legal Studies, Vol. 6, No. 1 (1986): 1-45, esp. 1, 5. Se DOI, 10.1 ...

* Law: see Jurisprudence; also Case theory
* Linguistics
Linguistics is the scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, objective, and precise analysis of all aspects of language, particularly its nature and structure. Linguis ...

: X-bar theory
In linguistics, X-bar theory is a model of phrase-structure grammar and a theory of syntactic category formation that was first proposed by Noam Chomsky in 1970Chomsky, Noam (1970). Remarks on Nominalization. In: R. Jacobs and P. Rosenbaum (eds.) ...

— Government and Binding
A government is the system or group of people governing an organized community, generally a state.
In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is ...

— Principles and parameters — Universal grammar
Universal grammar (UG), in modern linguistics, is the theory of the genetic component of the language faculty, usually credited to Noam Chomsky. The basic postulate of UG is that there are innate constraints on what the grammar of a possible hu ...

* Literature: Literary theory
Literary theory is the systematic study of the nature of literature and of the methods for literary analysis. Culler 1997, p.1 Since the 19th century, literary scholarship includes literary theory and considerations of intellectual history, mo ...

* Mathematics: Approximation theory
In mathematics, approximation theory is concerned with how function (mathematics), functions can best be approximation, approximated with simpler functions, and with quantitative property, quantitatively characterization (mathematics), characteri ...

— Arakelov theory In mathematics, Arakelov theory (or Arakelov geometry) is an approach to Diophantine geometry, named for Suren Arakelov. It is used to study Diophantine equations in higher dimensions.
Background
The main motivation behind Arakelov geometry is t ...

— Asymptotic theory
In mathematical analysis, asymptotic analysis, also known as asymptotics, is a method of describing limiting behavior.
As an illustration, suppose that we are interested in the properties of a function as becomes very large. If , then as bec ...

— Bifurcation theory
Bifurcation theory is the mathematical study of changes in the qualitative or topological structure of a given family of curves, such as the integral curves of a family of vector fields, and the solutions of a family of differential equations. ...

— Catastrophe theory — Category theory — Chaos theory
Chaos theory is an interdisciplinary area of scientific study and branch of mathematics focused on underlying patterns and deterministic laws of dynamical systems that are highly sensitive to initial conditions, and were once thought to have co ...

— Choquet theory In mathematics, Choquet theory, named after Gustave Choquet, is an area of functional analysis and convex analysis concerned with measures which have support on the extreme points of a convex set ''C''. Roughly speaking, every vector of ''C'' sho ...

— Coding theory
Coding theory is the study of the properties of codes and their respective fitness for specific applications. Codes are used for data compression, cryptography, error detection and correction, data transmission and data storage. Codes are stud ...

— Combinatorial game theory
Combinatorial game theory is a branch of mathematics and theoretical computer science that typically studies sequential games with perfect information. Study has been largely confined to two-player games that have a ''position'' that the player ...

— Computability theory
Computability theory, also known as recursion theory, is a branch of mathematical logic, computer science, and the theory of computation that originated in the 1930s with the study of computable functions and Turing degrees. The field has since e ...

— Computational complexity theory
In theoretical computer science and mathematics, computational complexity theory focuses on classifying computational problems according to their resource usage, and relating these classes to each other. A computational problem is a task solved by ...

— Deformation theory — Dimension theory
In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coord ...

— Ergodic theory
Ergodic theory (Greek: ' "work", ' "way") is a branch of mathematics that studies statistical properties of deterministic dynamical systems; it is the study of ergodicity. In this context, statistical properties means properties which are expres ...

— Field theory — Galois theory
In mathematics, Galois theory, originally introduced by Évariste Galois, provides a connection between field theory and group theory. This connection, the fundamental theorem of Galois theory, allows reducing certain problems in field theory to ...

— Game theory
Game theory is the study of mathematical models of strategic interactions among rational agents. Myerson, Roger B. (1991). ''Game Theory: Analysis of Conflict,'' Harvard University Press, p.&nbs1 Chapter-preview links, ppvii–xi It has appli ...

— Graph theory
In mathematics, graph theory is the study of ''graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conne ...

— Group theory
In abstract algebra, group theory studies the algebraic structures known as group (mathematics), groups.
The concept of a group is central to abstract algebra: other well-known algebraic structures, such as ring (mathematics), rings, field ...

— Hodge theory — Homology theory — Homotopy theory — Ideal theory
In mathematics, ideal theory is the theory of ideals in commutative rings. While the notion of an ideal exists also for non-commutative rings, a much more substantial theory exists only for commutative rings (and this article therefore only consid ...

— Intersection theory
In mathematics, intersection theory is one of the main branches of algebraic geometry, where it gives information about the intersection of two subvarieties of a given variety. The theory for varieties is older, with roots in Bézout's theorem o ...

— Invariant theory
Invariant theory is a branch of abstract algebra dealing with actions of groups on algebraic varieties, such as vector spaces, from the point of view of their effect on functions. Classically, the theory dealt with the question of explicit descri ...

— Iwasawa theory
In number theory, Iwasawa theory is the study of objects of arithmetic interest over infinite towers of number fields. It began as a Galois module theory of ideal class groups, initiated by (), as part of the theory of cyclotomic fields. In th ...

— K-theory
In mathematics, K-theory is, roughly speaking, the study of a ring generated by vector bundles over a topological space or scheme. In algebraic topology, it is a cohomology theory known as topological K-theory. In algebra and algebraic geometry, ...

— KK-theory
In mathematics, ''KK''-theory is a common generalization both of K-homology and K-theory as an additive bivariant functor on separable C*-algebras. This notion was introduced by the Russian mathematician Gennadi Kasparov in 1980.
It was influ ...

— Knot theory
In the mathematical field of topology, knot theory is the study of knot (mathematics), mathematical knots. While inspired by knots which appear in daily life, such as those in shoelaces and rope, a mathematical knot differs in that the ends are ...

— L-theory
In mathematics, algebraic ''L''-theory is the ''K''-theory of quadratic forms; the term was coined by C. T. C. Wall,
with ''L'' being used as the letter after ''K''. Algebraic ''L''-theory, also known as "Hermitian ''K''-theory",
is important in ...

— Lie theory
In mathematics, the mathematician Sophus Lie ( ) initiated lines of study involving integration of differential equations, transformation groups, and contact of spheres that have come to be called Lie theory. For instance, the latter subject is L ...

— Littlewood–Paley theory — Matrix theory
In mathematics, a matrix (plural matrices) is a rectangular array or table of numbers, symbols, or expressions, arranged in rows and columns, which is used to represent a mathematical object or a property of such an object.
For example,
\begi ...

— Measure theory
In mathematics, the concept of a measure is a generalization and formalization of geometrical measures ( length, area, volume) and other common notions, such as mass and probability of events. These seemingly distinct concepts have many simil ...

— Model theory
In mathematical logic, model theory is the study of the relationship between formal theories (a collection of sentences in a formal language expressing statements about a mathematical structure), and their models (those structures in which the s ...

— Morse theory
In mathematics, specifically in differential topology, Morse theory enables one to analyze the topology of a manifold by studying differentiable functions on that manifold. According to the basic insights of Marston Morse, a typical differentiabl ...

— Nevanlinna theory In the mathematical field of complex analysis, Nevanlinna theory is part of the
theory of meromorphic functions. It was devised in 1925, by Rolf Nevanlinna. Hermann Weyl called it "one of the few great mathematical events of (the twentieth) century ...

— Number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic function, integer-valued functions. German mathematician Carl Friedrich Gauss (1777 ...

— Obstruction theory In mathematics, obstruction theory is a name given to two different mathematical theories, both of which yield cohomological invariants.
In the original work of Stiefel and Whitney, characteristic classes were defined as obstructions to the ex ...

— Operator theory
In mathematics, operator theory is the study of linear operators on function spaces, beginning with differential operators and integral operators. The operators may be presented abstractly by their characteristics, such as bounded linear operators ...

— PCF theory — Perturbation theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middl ...

— Potential theory
In mathematics and mathematical physics, potential theory is the study of harmonic functions.
The term "potential theory" was coined in 19th-century physics when it was realized that two fundamental forces of nature known at the time, namely gra ...

— Probability theory
Probability theory is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expressing it through a set o ...

— Ramsey theory
Ramsey theory, named after the British mathematician and philosopher Frank P. Ramsey, is a branch of mathematics that focuses on the appearance of order in a substructure given a structure of a known size. Problems in Ramsey theory typically ask ...

— Rational choice theory
Rational choice theory refers to a set of guidelines that help understand economic and social behaviour. The theory originated in the eighteenth century and can be traced back to political economist and philosopher, Adam Smith. The theory postula ...

— Representation theory
Representation theory is a branch of mathematics that studies abstract algebraic structures by ''representing'' their elements as linear transformations of vector spaces, and studies modules over these abstract algebraic structures. In essen ...

— Ring theory
In algebra, ring theory is the study of rings— algebraic structures in which addition and multiplication are defined and have similar properties to those operations defined for the integers. Ring theory studies the structure of rings, their re ...

— Set theory
Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly conce ...

— Shape theory — Small cancellation theory In the mathematical subject of group theory, small cancellation theory studies groups given by group presentations satisfying small cancellation conditions, that is where defining relations have "small overlaps" with each other. Small cancellation ...

— Spectral theory In mathematics, spectral theory is an inclusive term for theories extending the eigenvector and eigenvalue theory of a single square matrix to a much broader theory of the structure of operators in a variety of mathematical spaces. It is a result ...

— Stability theory — Stable theory
In the mathematical field of model theory, a complete theory is called stable if it does not have too many types. One goal of classification theory is to divide all complete theories into those whose models can be classified and those whose model ...

— Sturm–Liouville theory — Twistor theory
In theoretical physics, twistor theory was proposed by Roger Penrose in 1967 as a possible path to quantum gravity and has evolved into a branch of theoretical and mathematical physics. Penrose proposed that twistor space should be the basic are ...

* Music: Music theory
Music theory is the study of the practices and possibilities of music. ''The Oxford Companion to Music'' describes three interrelated uses of the term "music theory". The first is the "rudiments", that are needed to understand music notation (ke ...

* Philosophy: Proof theory
Proof theory is a major branchAccording to Wang (1981), pp. 3–4, proof theory is one of four domains mathematical logic, together with model theory, axiomatic set theory, and recursion theory. Jon Barwise, Barwise (1978) consists of four correspo ...

— Speculative reason
Speculative reason, sometimes called theoretical reason or pure reason, is theoretical (or logical, deductive) thought, as opposed to practical (active, willing) thought. The distinction between the two goes at least as far back as the ancient ...

— Theory of truth
Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dictionarytruth 2005 In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs ...

— Type theory
In mathematics, logic, and computer science, a type theory is the formal presentation of a specific type system, and in general type theory is the academic study of type systems. Some type theories serve as alternatives to set theory as a fou ...

— Value theory
In ethics and the social sciences, value theory involves various approaches that examine how, why, and to what degree humans value things and whether the object or subject of valuing is a person, idea, object, or anything else. Within philosophy, ...

— Virtue theory
Virtue ethics (also aretaic ethics, from Greek ἀρετή arete_(moral_virtue).html"_;"title="'arete_(moral_virtue)">aretḗ''_is_an_approach_to_ethics_that_treats_the_concept_of_virtue.html" ;"title="arete_(moral_virtue)">aretḗ''.html" ;" ...

* Physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

: Acoustic theory — Antenna theory
In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies a ...

— Atomic theory
Atomic theory is the scientific theory that matter is composed of particles called atoms. Atomic theory traces its origins to an ancient philosophical tradition known as atomism. According to this idea, if one were to take a lump of matter a ...

— BCS theory
BCS theory or Bardeen–Cooper–Schrieffer theory (named after John Bardeen, Leon Cooper, and John Robert Schrieffer) is the first microscopic theory of superconductivity since Heike Kamerlingh Onnes's 1911 discovery. The theory describes sup ...

— Dirac hole theory
Dirac hole theory is a theory in quantum mechanics, named after English theoretical physicist Paul Dirac. The theory poses that the continuum of negative energy states, that are solutions to the Dirac equation, are filled with electrons, and the ...

— Dynamo theory
In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can ...

— Landau theory
Landau theory in physics is a theory that Lev Landau introduced in an attempt to formulate a general theory of continuous (i.e., second-order) phase transitions. It can also be adapted to systems under externally-applied fields, and used as a qua ...

— M-theory
M-theory is a theory in physics that unifies all consistent versions of superstring theory. Edward Witten first conjectured the existence of such a theory at a string theory conference at the University of Southern California in 1995. Witten's ...

— Perturbation theory
In mathematics and applied mathematics, perturbation theory comprises methods for finding an approximate solution to a problem, by starting from the exact solution of a related, simpler problem. A critical feature of the technique is a middl ...

— Theory of relativity
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in ...

(successor to classical mechanics
Classical mechanics is a physical theory describing the motion of macroscopic objects, from projectiles to parts of machinery, and astronomical objects, such as spacecraft, planets, stars, and galaxies. For objects governed by classical ...

) — Quantum field theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines classical field theory, special relativity, and quantum mechanics. QFT is used in particle physics to construct physical models of subatomic particles and ...

— Scattering theory — String theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interac ...

— Quantum information theory
Quantum information is the information of the quantum state, state of a quantum system. It is the basic entity of study in quantum information theory, and can be manipulated using quantum information processing techniques. Quantum information re ...

* Psychology
Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ...

: Theory of mind
In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...

— Cognitive dissonance theory
In the field of psychology, cognitive dissonance is the perception of contradictory information, and the mental toll of it. Relevant items of information include a person's actions, feelings, ideas, beliefs, values, and things in the environment. ...

— Attachment theory
Attachment theory is a psychological, evolutionary and ethological theory concerning relationships between humans. The most important tenet is that young children need to develop a relationship with at least one primary caregiver for normal ...

— Object permanence
Object permanence is the understanding that objects continue to exist even when they cannot be sensed. This is a fundamental concept studied in the field of developmental psychology, the subfield of psychology that addresses the development of ...

— Poverty of stimulus
Poverty of the stimulus (POS) is the controversial argument from linguistics that children are not exposed to rich enough data within their linguistic environments to acquire every feature of their language. This is considered evidence contrary to ...

— Attribution theory
Attribution is a term used in psychology which deals with how individuals perceive the causes of everyday experience, as being either external or internal. Models to explain this process are called attribution theory. Psychological research into a ...

— Self-fulfilling prophecy — Stockholm syndrome
Stockholm syndrome is a condition in which hostages develop a psychological bond with their captors. It is supposed to result from a rather specific set of circumstances, namely the power imbalances contained in hostage-taking, kidnapping, an ...

* Public Budgeting Public budgeting is a field of public administration and a discipline in the academic study thereof. Budgeting is characterized by its approaches, functions, formation, and type.
Authors Robert W. Smith and Thomas D. Lynch describe public budgetin ...

: Incrementalism
:''In politics, the term "incrementalism" is also used as a synonym for Gradualism.''
Incrementalism is a method of working by adding to a project using many small incremental changes instead of a few (extensively planned) large jumps. Logical i ...

— Zero-based budgeting
Zero-based budgeting (ZBB) is a budgeting method that requires all expenses to be justified and approved in each new budget period. It was developed by Peter Pyhrr in the 1970s. This budgeting method analyzes an organization's needs and costs by ...

* Public Administration
Public Administration (a form of governance) or Public Policy and Administration (an academic discipline) is the implementation of public policy, administration of government establishment (public governance), management of non-profit establ ...

: Organizational theory
* Semiotics
Semiotics (also called semiotic studies) is the systematic study of sign processes ( semiosis) and meaning making. Semiosis is any activity, conduct, or process that involves signs, where a sign is defined as anything that communicates something ...

: Intertheoricity Transferogenesis

* Sociology:

Critical theory
A critical theory is any approach to social philosophy that focuses on society and culture to reveal, critique and challenge power structures. With roots in sociology and literary criticism, it argues that social problems stem more from soci ...

— Engaged theory
Engaged theory is a methodological framework for understanding social complexity. It takes social life or social relations as its base category, with 'the social' always understood as grounded in 'the natural', including humans as embodied beings. ...

— Social theory
Social theories are analytical frameworks, or paradigms, that are used to study and interpret social phenomena.Seidman, S., 2016. Contested knowledge: Social theory today. John Wiley & Sons. A tool used by social scientists, social theories rela ...

— Sociological theory
A sociological theory is a that intends to consider, analyze, and/or explain objects of social reality from a sociological perspective,Macionis, John and Linda M. Gerber. 2010. ''Sociology'' (7th Canadian ed.). Upper Saddle River, NJ: Pearson ...

– Social capital
Social capital is "the networks of relationships among people who live and work in a particular society, enabling that society to function effectively". It involves the effective functioning of social groups through interpersonal relationships ...

theory
* Statistics: Extreme value theory
Extreme value theory or extreme value analysis (EVA) is a branch of statistics dealing with the extreme deviations from the median of probability distributions. It seeks to assess, from a given ordered sample of a given random variable, the pr ...

* Theatre
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...

: Performance theory
* Visual Art: Aesthetics
Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed thr ...

— Art educational theory — Architecture — Composition
Composition or Compositions may refer to:
Arts and literature
*Composition (dance), practice and teaching of choreography
*Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include v ...

— Anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

— Color theory — Perspective — Visual perception
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflecte ...

— Geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...

— Manifold
In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point. More precisely, an n-dimensional manifold, or ''n-manifold'' for short, is a topological space with the property that each point has a n ...

s
* Other: Obsolete scientific theories
This list catalogs well-accepted theories in science and pre-scientific natural philosophy and natural history which have since been superseded by scientific theories. Many discarded explanations were once supported by a scientific consensus, b ...

See also

*Falsifiability
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book '' The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a s ...

* Hypothesis testing
A statistical hypothesis test is a method of statistical inference used to decide whether the data at hand sufficiently support a particular hypothesis.
Hypothesis testing allows us to make probabilistic statements about population parameters.
...

* Physical law
Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow) ...

* Predictive power
The concept of predictive power, the power of a scientific theory to generate testable predictions, differs from '' explanatory power'' and ''descriptive power'' (where phenomena that are already known are retrospectively explained or describe ...

* Testability
Testability is a primary aspect of Science and the Scientific Method and is a property applying to an empirical hypothesis, involves two components:
#Falsifiability or defeasibility, which means that counterexamples to the hypothesis are logicall ...

* Theoretical definition
A theoretical definition defines a term in an academic discipline, functioning as a proposal to see a phenomenon in a certain way. A theoretical definition is a proposed way of thinking about potentially related events. Theoretical definitions cont ...

Notes

References

Citations

Sources

* Davidson Reynolds, Paul (1971). ''A primer in theory construction''. Boston: Allyn and Bacon. * Guillaume, Astrid (2015). « Intertheoricity: Plasticity, Elasticity and Hybridity of Theories. Part II: Semiotics of Transferogenesis », in ''Human and Social studies'', Vol.4, N°2 (2015), éd.Walter de Gruyter, Boston, Berlin, pp. 59–77. * Guillaume, Astrid (2015). « The Intertheoricity : Plasticity, Elasticity and Hybridity of Theories », in ''Human and Social studies'', Vol.4, N°1 (2015), éd.Walter de Gruyter, Boston, Berlin, pp. 13–29. * Hawking, Stephen (1996). ''A Brief History of Time'' (Updated and expanded ed.). New York: Bantam Books, p. 15. * * . * Popper, Karl (1963), ''Conjectures and Refutations'', Routledge and Kegan Paul, London, UK, pp. 33–39. Reprinted inTheodore Schick
Theodore Schick is an American author in the field of philosophy.
His articles have appeared in numerous publications and include topics such as functionalism and its effect on immortality, the logic behind the criteria of adequacy, and applyin ...

(ed., 2000), ''Readings in the Philosophy of Science'', Mayfield Publishing Company, Mountain View, California, USA, pp. 9–13.
* Zima, Peter V. (2007). "What is theory? Cultural theory as discourse and dialogue". London: Continuum (translated from: Was ist Theorie? Theoriebegriff und Dialogische Theorie in der Kultur- und Sozialwissenschaften. Tübingen: A. Franke Verlag, 2004).
External links

"How science works: Even theories change"

''Understanding Science'' by the University of California Museum of Paleontology.

{{Authority control Abstraction Conceptual systems Inductive reasoning Ontology