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Critical Thinking

Philosophers, mental models, and thinking traps — explained for kids.

470-399 BCEAncient Greece

Socrates

Socrates taught by asking questions instead of giving answers. He believed that good questions help us think better.

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428-348 BCEAncient Greece

Plato

Plato believed that everything we see is just an imperfect copy of a perfect version that exists in the world of ideas.

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384-322 BCEAncient Greece

Aristotle

Aristotle taught that the best way is usually in the middle - not too much and not too little. Courage is between cowardice and recklessness.

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121-180 CERoman Empire

Marcus Aurelius

Marcus Aurelius was a Roman Emperor who taught that we should focus on our own thoughts and actions, not worry about things we can't control.

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1596-1650France

René Descartes

Descartes tried to doubt everything he could, and found one thing he couldn't doubt: that he was thinking! If he's thinking, he must exist.

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1724-1804Prussia (Germany)

Immanuel Kant

Kant said: Before you do something, ask yourself "What if everyone did this?" If that would be bad, don't do it.

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1806-1873England

John Stuart Mill

Mill taught that the right choice is the one that creates the most happiness for the most people. But quality of happiness matters too.

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Cognitive bias

Confirmation Bias

Looking for proof you're right, instead of checking if you're wrong

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Cognitive bias

Sunk Cost Fallacy

The "I already started so I have to finish" trap

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Cognitive bias

Availability Heuristic

Thinking things are common just because they're easy to remember

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Cognitive bias

Dunning-Kruger Effect

Thinking you're an expert after learning just a little bit

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Cognitive bias

Survivorship Bias

Forgetting about all the people who tried and failed

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Thought experimentBeginner

The Cookie Jar

If you take a cookie when no one is watching and no one finds out, is it still wrong?

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Thought experimentIntermediate

Plato's Cave

Imagine prisoners in a cave who can only see shadows on the wall. They think shadows are reality. One prisoner escapes and sees the real world. When they…

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Thought experimentIntermediate

Ship of Theseus

A ship has every single plank replaced, one by one, over many years. Is it still the same ship? What if someone rebuilds a ship from all the old planks -…

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Thought experimentAdvanced

The Trolley Problem

A runaway trolley is heading toward 5 people who will die. You can pull a lever to divert it to a track with 1 person who will die. What do you do?

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Thought experimentAdvanced

The Experience Machine

Scientists create a machine that can give you any experience you want - you'd feel like you're living your dream life. But it's all fake - you're…

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Mental modelproblem-solving

First Principles Thinking

Break complex problems down to fundamental truths

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Mental modelself-awareness

Circle of Competence

Know what you know and what you don't know

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Mental modeldecision-making

Second-Order Thinking

Think beyond the first consequence - what happens next?

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Mental modelproblem-solving

Inversion

Think backwards - instead of how to succeed, think how to fail

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Mental modelgrowth

Compound Effects

Small consistent actions multiply over time

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Mental modeldecision-making

Opportunity Cost

Every choice means saying no to something else

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Explore the full Critical Thinking module →