Thank you for visiting this site. This article gathers the world’s most famous thought experiments into a single list.
A thought experiment is a method of testing a concept or position by setting up an imaginary situation purely in the mind and reasoning out what would follow, without ever running a real experiment. From the philosophers of ancient Greece to scientists like Galileo and Einstein, many of the greatest minds have used thought experiments to open up entirely new insights.
This article presents a curated set of famous thought experiments from every field — philosophy of mind, epistemology, ethics, political philosophy, and physics. Each one links to a full standalone explanation, so follow any that catch your interest.
Thought Experiments vs. Paradoxes
Thought experiments are often confused with paradoxes, but the two are different.
A “paradox” is a problem in which a seemingly valid premise or chain of reasoning leads to a contradictory or counterintuitive conclusion. A “thought experiment,” by contrast, is a method of setting up an imaginary scenario in the mind and reasoning about what happens in order to test a concept or position.
For example, “Laplace’s Demon” is a thought experiment designed to illustrate determinism — the idea that an intellect knowing the state of every particle could predict the future perfectly. It produces no contradiction in itself, so strictly speaking it is a thought experiment rather than a paradox.
The boundary is blurry, however. Cases like “Schrodinger’s Cat” and “Maxwell’s Demon” are thought experiments that also carry an apparent contradiction (a paradox). In this article we treat as thought experiments those cases whose main point is testing a concept through reasoning about an imagined situation, rather than deriving a contradiction.
For paradoxes, we have a separate list — please see it as well.
Thought Experiments of Mind & Consciousness
These thought experiments tackle the hardest questions about our inner life: “What is the mind?” and “Where does consciousness come from?” In the age of AI, they are drawing fresh attention.
| Thought Experiment | In One Line |
|---|---|
| The Chinese Room | Does an AI that only manipulates symbols truly “understand”? |
| Philosophical Zombie | Could a copy of a human exist that lacks only consciousness? |
| Mary’s Room | Does a scientist who knows all the facts about color learn something on first seeing it? |
| What Is It Like to Be a Bat? | Can subjective experience be explained by objective science? |
Thought Experiments of Knowledge & Reality
“Is the world I see real?” — these thought experiments about reality and perception have troubled philosophers since antiquity, and are famous as the inspiration behind the film The Matrix.
| Thought Experiment | In One Line |
|---|---|
| Brain in a Vat | How can a brain in a tank disprove the fake world it is shown? |
| Descartes’ Evil Demon | After doubting everything, what is left that cannot be doubted? |
| The Simulation Argument | Is our universe a simulation run by an advanced civilization? |
Thought Experiments of Personal Identity
“Is the me of yesterday the same as the me of today?” “Is a copy of me still me?” — these thought experiments probe the identity of the self.
| Thought Experiment | In One Line |
|---|---|
| The Teletransporter | Is a person disassembled and rebuilt the same as the original? |
Thought Experiments of Ethics & Morality
These thought experiments make us ask “what is the right thing to do?” By setting up extreme situations, they expose the true shape of our moral intuitions.
| Thought Experiment | In One Line |
|---|---|
| The Trolley Problem | Is it permissible to sacrifice one to save five? |
| The Experience Machine | Would you choose to live plugged into a machine of happiness? |
| The Ring of Gyges | Would people stay just even if they could turn invisible? |
| The Violinist | How far does the duty to keep another person alive extend? |
Thought Experiments of Political Philosophy
A thought experiment for asking “what does a just society look like?” If you didn’t know what position you would be born into, what rules would you choose?
| Thought Experiment | In One Line |
|---|---|
| The Veil of Ignorance | Not knowing your own situation, what society would you choose? |
Thought Experiments of Physics & Science
Physicists run experiments not only in the lab but also in their heads. Many of the great discoveries in the history of science — including Einstein’s relativity — were born from thought experiments.
| Thought Experiment | In One Line |
|---|---|
| Laplace’s Demon | If an intellect knew everything, is the future already fixed? |
| Einstein’s Elevator | Are gravity and acceleration really indistinguishable? |
| Boltzmann Brain | The universe may contain more “accidental brains” than people like you |
Summary
This article presented a list of the world’s famous thought experiments.
The wonderful thing about thought experiments is that they require no expensive equipment and no dangerous experiments — you can reach the essence of the world using your mind alone. And many of them shake the very assumptions we take for granted: what consciousness is, what reality is, what rightness is.
Plato’s “Ring of Gyges,” proposed over 2,000 years ago, still probes the foundations of morality today. Einstein’s “elevator thought experiment” gave birth to general relativity, one of humanity’s greatest intellectual achievements. And the Chinese Room is debated more fiercely than ever now that AI is part of everyday life.
Each thought experiment has its own full explanation linked above, so do read any that interest you. The more you think, the more the world looks different.
There is also an index of “Strategic Thinking Frameworks” covering game theory, behavioral economics, and more. If you like thought experiments about decision-making such as the Trolley Problem, I think you will enjoy that series as well.
Thank you for reading. We hope to see you in the next article.
📚 Series: Famous Thought Experiments (1/17)