Theory

A theory is a set of ideas about something. People create theories using different ways of thinking and for many reasons.

When we talk about theories in school or other learning places, they are a careful and rational way to think about something. This kind of thinking uses logical reasoning. It is often helped by watching things, trying experiments, and doing research. Theories can be about science and can be checked through tests, or they can be about things like art or philosophy. Sometimes, theories are not tied to any special subject.

In modern science, a "theory" means a scientific theory. This is a well-checked way to explain nature. It is done in a way that fits the scientific method and meets the criteria of modern science. Scientific theories are written so that tests can show if they are right or wrong. They are the most trusted and complete kind of scientific knowledge. This is different from everyday use of the word "theory," which can mean something that is not proven. In science, an unproven idea is better called a hypothesis.

Ancient usage

The word theory comes from an old Ancient Greek word meaning "looking at" or "viewing." Over time, it came to mean careful, logical ideas about how nature works. Famous thinkers like Pythagoras and Aristotle used the idea of theory to talk about calm, rational thinking about the world, not just doing things to change it.

These early uses helped shape what we mean by theory today — a way to understand the world through thought and reason.

Formality

Theories help us understand, explain, and predict things. We use them in many areas, like science and art. A formal theory is a group of ideas that only makes sense when we use it with real facts or events. Theories can be written in simple words or in special math languages.

Theories are made of statements we think are true about a subject. But, these statements are only true when we look at the whole theory. Sometimes, two different theories can make the same predictions and explain things just as well. In math, theories are studied using special rules and starting points called axioms. These help us find new true statements, called theorems, which can solve real-world problems. For example, math helps us understand numbers, space, and chances.

Theory–practice relationship

Theory is often different from practice, or the actual doing of something. Scholars in fields like medicine, engineering, law, and management wonder if ideas and models from theory really help in real work. Sometimes, there is a gap between what research tells us and what people actually do. Some say that academics don’t always share their knowledge well with practitioners.

One idea suggests that theory and practice look at problems in different ways, using different ways of understanding the world. In management, some scholars suggest a way called "engaged scholarship," where they study real problems from different angles. This creates both useful practical results and new theories, shared in academic ways. They compare this to moving ideas between different areas of study.

Scientific

Main article: Scientific theory

In science, a theory is an explanation of how nature works. It is based on facts learned through observation and testing. Scientific theories can make predictions that can be tested.

Scientific theories help scientists understand the world. They are used to make new discoveries, create technology, and solve problems. For example, theories about cells and atoms are so well-known that they are accepted as facts. Theories can be improved or replaced when new evidence is found. This leads to better understanding over time.

Mathematical

See also: List of mathematical theories

In mathematics, the word theory has a special meaning. It means a big area of math that studies certain ideas or ways of doing things. Examples include set theory, where we look at groups of objects, and number theory, which studies the properties of numbers.

In mathematical logic, a theory is a set of ideas, or theorems, that we can prove using some basic rules called axioms and steps called inference rules. This helps mathematicians learn new things one step at a time.

Philosophical

Main article: Philosophical theory

A theory can describe things, like in science, or it can give rules about how things should be, like in philosophy. Philosophical theories deal with ideas instead of things we can see or touch. Some important ideas in philosophy cannot be proven true just by looking at the world around us.

Fields of study are sometimes called "theories" because they start with certain basic ideas or rules. These starting points are like the building blocks for the whole field. Examples include set theory and number theory, but also literary theory, critical theory, and music theory.

Main article: Metatheory

A special kind of philosophical theory is called a metatheory. This is a theory about other theories. It looks at theories themselves and makes statements about how they work. These statements are known as metatheorems.

Political

Main article: Political theory

A political theory is an idea about how laws and governments should work. It is a way to think about what is right or wrong in running a country. People use political theories to consider how societies should be organized and led.

Jurisprudential

Main articles: Jurisprudence and Law

In social science, jurisprudence is the study of ideas about law. It asks questions about how laws work and what makes a law fair. This helps us understand the thoughts behind laws and how they fit into our lives.

Examples

Many areas use theories to explain and predict things. Most are scientific theories, but some come from other areas like music or art. For example:

• Anthropology: Carneiro's circumscription theory
• Astronomy: Alpher–Bethe–Gamow theory, B²FH Theory, Copernican theory, Newton's theory of gravitation, Hubble's law, Kepler's laws of planetary motion, Ptolemaic theory
• Biology: Cell theory, Chemiosmotic theory, Evolution, Germ theory, Symbiogenesis
• Chemistry: Molecular theory, Kinetic theory of gases, Molecular orbital theory, and many others
• Climatology: Climate change theory, anthropogenic climate change and global warming theories
• Computer Science: Automata theory, Queueing theory
• Cosmology: Big Bang Theory, Cosmic inflation, Loop quantum gravity, Superstring theory, and more
• Economics: Macroeconomic theory, Microeconomic theory, Law of Supply and demand
• Education: Constructivist theory, Critical pedagogy theory, Education theory, and others
• Engineering: Circuit theory, Control theory, Signal theory, Systems theory, Information theory
• Film: Film theory
• Geology: Plate tectonics
• Humanities: Critical theory
• Jurisprudence or 'Legal theory': Natural law, Legal positivism, Legal realism, Critical legal studies
• Law: see Jurisprudence; also Case theory
• Linguistics: X-bar theory, Government and Binding, Principles and parameters, Universal grammar
• Literature: Literary theory
• Mathematics: Approximation theory, Category theory, Chaos theory, Game theory, and many more
• Music: Music theory
• Philosophy: Proof theory, Theory of truth, Type theory, and others
• Physics: Atomic theory, Theory of relativity, Quantum field theory, String theory, and others
• Psychology: Cognitive dissonance theory, Attachment theory, Attribution theory, and more
• Public Budgeting: Incrementalism, Zero-based budgeting
• Public Administration: Organizational theory
• Semiotics: Intertheoricity
• Sociology: Critical theory, Social theory, Sociological theory, and more
• Statistics: Extreme value theory
• Theatre: Performance theory
• Visual Arts: Aesthetics, Color theory, Perspective, and others

Other areas also have theories, including some that are no longer considered accurate science.