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Over 50 biases. One truth: your brain was built for speed, not accuracy, and it still runs the same shortcuts it did 200,000 years ago. This is the vulnerabilities track, the mental defaults that make you an easy target before anyone even tries to persuade you of anything.
JOIN THE CLUBSix quick answers before you go deep on any single bias.
A mental shortcut your brain uses to make fast decisions without stopping to reason through every detail. It's not a personal flaw or a sign you're not smart enough. Every brain, including the ones studying this, runs on these shortcuts.
These shortcuts are inherited, not installed by accident. For most of human history, a fast wrong-ish guess about a threat or a stranger beat a slow accurate one. Speed kept people alive. The wiring that helped an ancestor decide fast is the same wiring misfiring today.
Advertisers, political campaigns, algorithms, and most of the propaganda techniques in the book. A bias is a lock. Propaganda techniques are the key someone else made to fit it.
No. Everyone runs on these defaults, regardless of intelligence, education, or how careful a thinker they are. What changes is whether you know a shortcut is running and can catch it in the moment it matters.
Scrolling, shopping, arguing with family, meeting someone new, voting, deciding whether a headline is true. Anywhere you're forming a quick judgment, a bias is doing some of the work for you, whether you notice or not.
A fallacy is a flaw in an argument, something said out loud that doesn't hold up. A bias runs before any argument even starts. It shapes what you notice, believe, and remember before you've reasoned about anything at all.
Every entry works the same way. No academic language. No filler. If a section has nothing real to say, we leave it out instead of padding it.
What the bias is, plus the adaptive reason your brain runs it at all.
How hard this one is to catch when it's running in your own head, and why.
The psychology behind it, grounded in real research.
Everyday and real-world, not hypothetical.
Personal self-check moves, tiered by how much effort they take.
Which propaganda techniques exploit this bias, and how.
Primary sources and accessible further reading.
Every bias page carries a self-check difficulty rating: how hard that shortcut is to catch while it's actively running in your own thinking. Some biases are easy to spot in someone else's argument, but nearly invisible in your own head, that gap is itself one of the biases on this list.
Others are quick to catch once you know the one moment to watch for. It's not a "how harmful is this" score. It's a "how much self-awareness does catching this take, in the moment, before the decision is already made" score.
Every bias belongs to a cluster. Click through to the full page.
Biases that protect how you see yourself.
Biases that pull you toward the group.
Biases that distort what you remember or notice.
Biases that skew how you weigh choices.
Biases that miscalibrate danger.
Biases that find order where there may be none.
None of these are bugs. They're the same fast, low-effort thinking that let a distant ancestor decide in half a second whether a rustle in the grass was wind or a predator, whether a stranger was safe or a threat, whether the group's read on a situation was more trustworthy than one person's slow calculation.
That thinking was rewarded with survival. It never had to be updated for headlines, algorithms, or a stranger's political ad.
Calling a bias "wrong" or "stupid" misses what it actually is: quick, ancient, well-intentioned, and running on inputs it was never built to handle. The self-check isn't about turning it off, you can't. It's about knowing when the fast answer might be the wrong tool for the decision in front of you.
This isn't a quiz to grade you. It's gamified training: spot the shortcut, name it, and practice catching it before it decides for you.
Do you know confirmation bias from cognitive dissonance?
Bigger tell of the sunk cost fallacy: finishing a bad movie, or refusing to sell a stock that's tanked?
Can you catch your own hindsight bias before you say "I knew it all along"?
If any of those made you pause, your critical thinking has room to grow, and that's exactly what the Gym is built for. Get notified when it launches.
Free account. No ads pretending to be content. Just the techniques, the biases, and the training to catch both, straight to your inbox the moment the Gym is live.