36 Theory Examples – Most Famous Theories

theories examples definition

A theory is a set of coherent ideas and general principles that can be used to make meaning of the world around us.

There are theories in just about every academic discipline, including the physical sciences, social sciences, and philosophy.

Below are some theory examples that present some of the most famous theories from the following disciplines:

Note that this is by no means a comprehensive list. Furthermore, I’ve attempted to provide single-sentence explanations of each theory for brevity’s sake, but it’s of course impossible to fully explain a theory in one sentence. So, these explanations are highly simplified.

Theory Examples

Scientific Theories

1. Evolution – The theory that all living beings (plants, animals, humans, etc.) have evolved from a common ancestor.

2. Theory of General Relativity – The theory that explains that gravity is the curvature of spacetime caused by mass and energy.

3. The Big Bang – The theory that the universe emerged from a ‘singularity’ – one infinitely hot and dense event from which all mass and energy emerged.

4. Quantum Theory – The theory that particles’ states are only determined upon observation. It demonstrates that subatomic particles exhibit both wave-like and particle-like properties and can be in multiple states or locations at the same time.

5. Many Worlds Hypothesis – If we were to follow the logic of Quantum Theory, we end up with a hypothesis that there are many parallel worlds (universes) in which particles behave differently upon observation.

6. Heliocentrism – The theory that the solar system revolves around the sun. Before this theory, it was believed that everything revolved around the earth.

Sociological Theories

1. Conflict TheoryConflict theory sees the social world in terms of power conflict between the haves and have nots. In classical conflict theory, it explores the conflict between the capitalist class and workers.

2. Modernism – In sociology, modernism was a theoretical approach that explored capitalist and late capitalist societies by proposing that the scientific method and empiricism can help society become more efficient, wealthier, and more enlightened.

3. PostmodernismPostmodernism challenges modernism by proposing that people in power can shape how truth is understood. Historically, truth was shaped by religion. In the era of Modernism, it was shaped by scientific discourse which is more fallible than we might have first presupposed.

4. Symbolic InteractionismSymbolic interactionism proposes that language and social interactions shape how people make meaning of the world. It sees our interpretations of the world as being inherently culturally and socially mediated (see also: interactionst perspective in sociology).

5. FunctionalismFunctionalism in sociology sees society as a series of interrelated parts that, combined, maintain social order. Like the organs in the body, each part has its on role. Some important social institutions that maintain society, according to functionalism, include families, marriage, gender roles, government, schools, and the legal system. See more examples of functionalism here, or for here for functionalist theory in psychology.

6. FeminismFeminism is a theory that sees the world as being fundamentally patriarchal and advocates for a breakdown of the patriarchy to achieve equality between genders and sexes. There are four waves of feminism, each with unique perspectives and goals.

7. IntersectionalityIntersectionality is a theory that critiques critical theory and feminism by highlighting how they view social conflict through just one dimension. Instead, intersectionality proposes that the social world is structured through the overlap of social categories, including race, class, gender, age, (dis)ability, and sexuality.

8. Critical TheoryCritical theory is concerned with power imbalances. It aims to reveal the ways power is wielded by the dominant groups in society in ways designed to oppress the marginalized.

See 25 More Sociological Theories Here

Psychological Theories

1. Social Learning TheorySocial learning theory proposes that people’s cognitive development is dependant upon the influential people around them. It highlights the importance of social interaction in learning.

2. Self-Determination TheorySelf-determination theory is a theory of motivation that argues humans have three key psychological needs that affect our levels of intrinsic motivation. The three needs are: autonomy, competence, and relatedness.

3. BehaviorismBehaviorism proposes that people’s and animals’ behaviors are shaped by a series of rewards and punishments.

4. ConstructivismConstructivism proposes that people ‘construct’ knowledge in their minds into packets called schema. When we come across new experiences, we engage in cognitive processes, including assimilation and accommodation, in order to achieve cognitive equilibrium.

5. Cognitive Development TheoryCognitive development theory proposes that people’s brains develop in a series of stages that correspond with biological development. According to Piaget, the linear stages are: sensorimotor, preoperational, concrete operational, and formal operational.

6. Social Exchange TheorySocial exchange theory looks at social relationships as a function of simple cost-benefit analysis.

7. Psychoanalysis – Freud’s theory of psychoanalysis holds that unconscious desires influence an individual’s thoughts, feelings, and behaviors. In this theory, people pass through stages of internal conflict that they need to overcome in order to become a psychologically balanced adult.

See 33 More Psychology Theories Here

Economic Theories

1. Classical Economics – Classical economics proposes that economies are most efficient when left to market forces. 

2. Neoliberalism An extension of capitalism, neoliberalism advocates for the withdrawal of market regulation and promotion of market competition through policies such as deregulation and privatization.

3. Keynesian Economics – Keysianism holds that government intervention in economies can stimulate growth, decrease unemployment, and control the excessive inequalities of capitalism.

4. Monetarism – A theory that holds that the control of supply of money into the economy enables central banks to control inflation and economic growth to smooth out economic highs and lows.

5. Behavioral economics – This theory explores how individual and social behaviors affect economic behaviors. It helps policy makers to implement policies that change consumer behaviors to achieve economic goals.

Philosophical Theories

1. Stoicism – Stoicism believes in accepting what you cannot control and focussing on what you can in order to live a happy life.

2. ExistentialismExistentialism believes that there is no inherent purpose in life, so people are burdened with having to make choices and come to their own conclusions about how to live a personally meaningful life.

3. EmpiricismEmpiricism holds that knowledge fundamentally comes from experience and observation. Humans rely on the five senses and reasoning to come to their conclusions.

4. UtilitarianismUtilitarianism holds that the right and moral action is always the action that achieves the greatest happiness for the most number of people.

5. DeterminismDeterminism refers to the idea that future events have been determined by past actions and we cannot control our own fate.

6. HumanismHumanism holds that human flourishing on this earth is the most important goal of life. It advocates for human rights and a focus on individual happiness above all else.

Political Theories

1. Republicanism – A theory that societies should be self-governing. It arose as a response to monarchism and generally advocates for representative democracy.

2. Monarchism – A theory that societies are best served when a benevolent dictator is in charge. They are given their title by birthright. While absolute monarchy is seemingly absurd in the 21st Century, it’s still believed by many countries with a constitutional monarchy that a monarch with limited powers ensures political stability.

3. CommunismThe theory that holds that the means of production should be held by the government as the representative of the people and the ideal society is classless with equal distribution of resources.

4. LibertarianismThe theory that sovereign individuals should not be told what to do and government should not have the right to tell people how to live their lives or take money from individual through taxation.

5. Third Way – The third way political theory advocates for a centrist model that takes the best of capitalism and the pros of socialism to create a society that balances individual rights and community needs.


Theories are very useful in helping us to make sense of the world around us. They’re often changing and evolving, and that’s the amazing strength of science and academic knowledge. Nevertheless, many of the above theories such as heliocentrism have been more-or-less static for centuries. While we still call it a theory, it’s now unfalsifiable that the earth revolves around the sun, and not the other way around!

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Dr. Chris Drew is the founder of the Helpful Professor. He holds a PhD in education and has published over 20 articles in scholarly journals. He is the former editor of the Journal of Learning Development in Higher Education. [Image Descriptor: Photo of Chris]

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