When you have a theory, you have a set of beliefs or principles that might not be proven yet. Does anyone have a good theory for where missing socks go when you do laundry?

A theory is a set of accepted beliefs or organized principles that explain and guide analysis and one of the ways that theory is defined is that it is different from practice, when certain principles are tested. For example, you could be a musician who plays well but who doesn't have a lot of experience with the theory of music. This word is a noun and comes from the Greek theoria, which means "contemplation or speculation."

Definitions of theory

n a belief that can guide behavior

“the architect has a theory that more is less”
“they killed him on the theory that dead men tell no tales”
(ethics) the theory that the pursuit of your own welfare in the basis of morality
hodgepodge, jumble, patchwork
a theory or argument made up of miscellaneous or incongruous ideas
Type of:
any cognitive content held as true

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

theories can incorporate facts and laws and tested hypotheses”
“true in fact and theory
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a theory that all complex systems can be completely understood in terms of their components
theory that inherited characteristics are transmitted by germ plasm
preformation, theory of preformation
a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell
scientific theory
a theory that explains scientific observations
field theory
(physics) a theory that explains a physical phenomenon in terms of a field and the manner in which it interacts with matter or with other fields
economic theory
(economics) a theory of commercial activities (such as the production and consumption of goods)
atomic theory, atomism, atomist theory, atomistic theory
(chemistry) any theory in which all matter is composed of tiny discrete finite indivisible indestructible particles
holism, holistic theory
the theory that the parts of any whole cannot exist and cannot be understood except in their relation to the whole
structural sociology, structuralism
a sociological theory based on the premise that society comes before individuals
structural anthropology, structuralism
an anthropological theory that there are unobservable social structures that generate observable social phenomena
big bang theory, big-bang theory
(cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature
nebular hypothesis
(cosmology) the theory that the solar system evolved from a hot gaseous nebula
planetesimal hypothesis
(cosmology) the theory that the solar system was formed by the gravitational accumulation of planetesimals
continuous creation theory, steady state theory
(cosmology) the theory that the universe maintains a constant average density with matter created to fill the void left by galaxies that are receding from each other
Newton's theory of gravitation, gravitational theory, theory of gravitation, theory of gravity
(physics) the theory that any two particles of matter attract one another with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them
theory that the total organization of an organism rather than the functioning of individual organs is the determinant of life processes
the theory that an increasing consumption of goods is economically beneficial
the economic theories of John Maynard Keynes who advocated government monetary and fiscal programs intended to stimulate business activity and increase employment
an economic theory advocating free competition and a self-regulating market
Malthusian theory, Malthusianism
Malthus' theory that population increase would outpace increases in the means of subsistence
an economic theory holding that variations in unemployment and the rate of inflation are usually caused by changes in the supply of money
atomic theory
a theory of the structure of the atom
cell doctrine, cell theory
(biology) the theory that cells form the fundamental structural and functional units of all living organisms; proposed in 1838 by Matthias Schleiden and by Theodor Schwann
undulatory theory, wave theory, wave theory of light
(physics) the theory that light is transmitted as waves
corpuscular theory, corpuscular theory of light
(physics) the theory that light is transmitted as a stream of particles
kinetic theory, kinetic theory of gases
(physics) a theory that gases consist of small particles in random motion
Einstein's theory of relativity, relativity, relativity theory, theory of relativity
(physics) the theory that space and time are relative concepts rather than absolute concepts
(physics) a theory that tries to link the four fundamental forces
quantum theory
(physics) a physical theory that certain properties occur only in discrete amounts (quanta)
indeterminacy principle, uncertainty principle
(quantum theory) the theory that it is impossible to measure both energy and time (or position and momentum) completely accurately at the same time
germ theory
(medicine) the theory that all contagious diseases are caused by microorganisms
information theory
(computer science) a statistical theory dealing with the limits and efficiency of information processing
Arrhenius theory of dissociation, theory of dissociation, theory of electrolytic dissociation
(chemistry) theory that describes aqueous solutions in terms of acids (which dissociate to give hydrogen ions) and bases (which dissociate to give hydroxyl ions); the product of an acid and a base is a salt and water
evolutionism, theory of evolution, theory of organic evolution
(biology) a scientific theory of the origin of species of plants and animals
Ostwald's theory of indicators, theory of indicators
(chemistry) the theory that all indicators are either weak acids or weak bases in which the color of the ionized form is different from the color before dissociation
theory of inheritance
(biology) a theory of how characteristics of one generation are derived from earlier generations
association theory, associationism
(psychology) a theory that association is the basic principle of mental activity
(psychology) a theory that reduces all mental phenomena to simple elements (sensations and feelings) that form complex ideas by association
a psychology based on the assumption that all mental process are useful to an organism in adapting to the environment
Gestalt psychology, configurationism
(psychology) a theory of psychology that emphasizes the importance of configurational properties
game theory, theory of games
(economics) a theory of competition stated in terms of gains and losses among opposing players
Type of:
thought that makes something comprehensible

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

“he proposed a fresh theory of alkalis that later was accepted in chemical practices”
hypothesis, possibility
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a hypothetical possibility, circumstance, statement, proposal, situation, etc.
the physically discrete element that Darwin proposed as responsible for heredity
framework, model, theoretical account
a hypothetical description of a complex entity or process
conjecture, speculation
a hypothesis that has been formed by speculating or conjecturing (usually with little hard evidence)
assumption, supposal, supposition
a hypothesis that is taken for granted
a theory that social and cultural events are determined by history
computer simulation, simulation
(computer science) the technique of representing the real world by a computer program
an intuitive assumption
base, basis, cornerstone, foundation, fundament, groundwork
the fundamental assumptions from which something is begun or developed or calculated or explained
mean sun
a theoretical sun that moves along the celestial equator at a constant speed and completes its annual course in the same amount of time the real sun takes at variable speeds
Copernican system
(astronomy) Copernicus' astronomical model in which the Earth rotates around the sun
Ptolemaic system
(astronomy) Ptolemy's model of the universe with the Earth at the center
(particle physics) a theory that involves an eleven-dimensional universe in which the weak and strong forces and gravity are unified and to which all the string theories belong
string theory
(particle physics) a theory that postulates that subatomic particles are one-dimensional strings
given, precondition, presumption
an assumption that is taken for granted
basic assumption, constatation, self-evident truth
an assumption that is basic to an argument
stochastic process
a statistical process involving a number of random variables depending on a variable parameter (which is usually time)
Type of:
concept, conception, construct
an abstract or general idea inferred or derived from specific instances

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