Theory
A theory is a contemplative and rational type of abstract or generalizing thinking, or the results of such thinking. Depending on the context, the results might, for example, include generalized explanations of how nature works. The word has its roots in ancient Greek, but in modern use it has taken on several related meanings.
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, which may or may not be associated with particular explanatory models. To theorize is to develop this body of knowledge.
As already in Aristotle’s definitions, theory is very often contrasted to “practice” (from Greek praxis, πρᾶξις) a Greek term for doing, which is opposed to theory because pure theory involves no doing apart from itself. A classical example of the distinction between “theoretical” and “practical” uses the discipline of medicine: medical theory involves trying to understand the causes and nature of health and sickness, while the practical side of medicine is trying to make people healthy. These two things are related but can be independent, because it is possible to research health and sickness without curing specific patients, and it is possible to cure a patient without knowing how the cure worked.
In modern science, the term “theory” refers to scientific theories, a well-confirmed type of explanation of nature, made in a way consistent with scientific method, and fulfilling the criteria required by modern science. Such theories are described in such a way that any scientist in the field is in a position to understand and either provide empirical support (“verify”) or empirically contradict (“falsify”) 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 is better characterized by the word hypothesis). Scientific theories are distinguished from hypotheses, which are individual empirically testable conjectures, and from scientific laws, which are descriptive accounts of how nature behaves under certain conditions.
Theory (noun)
Mental conception; reflection, consideration. 16th-18th c.
Theory (noun)
A phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. from 17th c.
Theory (noun)
The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. from 17th c.
Theory (noun)
A field of study attempting to exhaustively describe a particular class of constructs. from 18th c.
“Knot theory classifies the mappings of a circle into 3-space.”
Theory (noun)
A hypothesis or conjecture. from 18th c.
Theory (noun)
A set of axioms together with all statements derivable from them. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems).
“A theory is consistent if it has a model.”
Model (noun)
A person who serves as a subject for artwork or fashion, usually in the medium of photography but also for painting or drawing.
“The beautiful model had her face on the cover of almost every fashion magazine imaginable.”
Model (noun)
A person, usually an attractive female, hired to show items or goods to the public, such as items given away as prizes on a TV game show.
Model (noun)
A representation of a physical object, usually in miniature.
“The boy played with a model of a World War II fighter plane.”
Model (noun)
A simplified representation used to explain the workings of a real world system or event.
“The computer weather model did not correctly predict the path of the hurricane.”
Model (noun)
A style, type, or design.
“He decided to buy the turbo engine model of the sports car.”
Model (noun)
The structural design of a complex system.
“The team developed a sound business model.”
Model (noun)
A successful example to be copied, with or without modifications.
“He was a model of eloquence and virtue.”
“British parliamentary democracy was seen as a model for other countries to follow.”
Model (noun)
An interpretation function which assigns a truth value to each atomic proposition.
Model (noun)
An interpretation which makes a certain sentence true, in which case that interpretation is called a model of that sentence.
Model (noun)
A particular style, design, or make of a particular product.
“This year’s model features four doors instead of two.”
Model (noun)
An identifier of a product given by its manufacturer (also called model number).
Model (noun)
An animal that is used to study a human disease or pathology.
Model (noun)
Any copy, or resemblance, more or less exact.
Model (noun)
In software applications using the model-view-controller design pattern, the part or parts of the application that manage the data.
Model (adjective)
Worthy of being a model; exemplary.
Model (verb)
To display for others to see, especially in regard to wearing clothing while performing the role of a fashion model.
“She modelled the shoes for her friends to see.”
Model (verb)
To use as an object in the creation of a forecast or model.
“They modelled the data with a computer to analyze the experiment’s results.”
Model (verb)
To make a miniature model of.
“He takes great pride in his skill at modeling airplanes.”
Model (verb)
To create from a substance such as clay.
“The sculptor modelled the clay into the form of a dolphin.”
Model (verb)
To make a model or models.
Model (verb)
To be a model of any kind.
“The actress used to model before being discovered by Hollywood.”