Judgment can be trained
Everyone has opinions. You have a method.
In the age of AI that knows everything, one thing keeps gaining value: judgment. One question a day to train it. A contrarian thinking course, open to everyone.
The only course in contrarian thinking
The question of the day
Get sharper every day.
The ritual
Thirty seconds a day. That is all it asks.
You answer, without thinking too long
A short question, three options, the same for everyone. No account asked, no countdown. The right answer is rarely the first one that comes to mind, and that is the point.
The answer drops, with its story
Not just the right box: the experiment, the study or the event it comes from, named and dated. It is the anecdote that sticks, not the rule.
The lesson waits right behind
Every question comes from one of the twenty-six lessons of the course. One link, ten minutes, and you have the full reasoning rather than the anecdote alone.
The streak
What brings you back tomorrow.
One isolated question changes nothing. Three hundred questions spread over a year change the way you read a figure, a poll, a schedule promise. Everything is built so that regularity wins, never intensity.
A day counts as soon as you have answered. The streak holds the days in a row, and a freeze is earned every ten days: it covers one missed day, on its own. We do not punish a Sunday without signal, we protect the habit.
Ten questions, five right answers in a row, a lesson completed where a question came from, and the rare one: being right where fewer than a third were. Each is awarded by the database, never by the interface, and it is never taken back.
There is no score to push up, so nothing to optimise by answering at random. What you take away is what you remembered, and the only proof that counts is the certificate at the end of the course.
What remains
A habit, and a proof at the end.
An application that teaches something must be able to show it. Here the proof is not a score you hand yourself: it is a certificate earned at the exam, and a profile anyone can open.
“I did the course” commits no one. A dated certificate, verifiable from a link, does.
Start today.
Free. One question a day, the contrarian thinking course included, a certificate you earn.
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The course · included with your account
Reason has become free. Judgment has not.
AIs reason fast, without fatigue or ego, and they carry the consensus of everything ever written. What is becoming rare, and therefore precious, is the spark: knowing when the consensus is right, and when it is wrong.
That is what the contrarian thinking path trains: six levels built notably on the work of Kahneman, Tetlock, Galef, Thiel, Duke and Flyvbjerg, one lesson a day, spaced reviews, a final exam and a certificate you earn. Theory is learned there. The question of the day keeps it alive afterwards, thirty seconds at a time.
Contrarian thinking can be learned, and the full course is already here. Built to fit a busy life: the first lesson takes ten minutes, and every validated lesson stays yours for good.
References
They said it before us.
A century of research and practice converges on the same idea: judgment is not a gift. It is a discipline, and it is maintained through repetition.
“The most contrarian thing of all is not to oppose the crowd but to think for yourself.”
“Truth, or more precisely, an accurate understanding of reality, is the essential foundation for any good outcome.”
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.”
“The first principle is that you must not fool yourself. And you are the easiest person to fool.”
“It is remarkable how much long-term advantage we have gotten by trying to be consistently not stupid, instead of trying to be very intelligent.”
“What makes a decision great is not that it has a great outcome. A great decision is the result of a good process.”
“The strongest predictor of rising into the ranks of superforecasters is perpetual beta, the degree to which one is committed to belief updating and self-improvement.”
In the same research, this trait predicts three times better than intelligence. Judgment can be trained. Percentyl is where you do it, one question a day.
Original quotes. Full sources in the footer.³
The questions we already get
What people ask before they start.
Q.01How do you train your judgment?
Through short repetition and immediate feedback, not through reading alone. Percentyl asks one question a day, drawn from a lesson of its contrarian thinking course: three options, one tap, and the answer right away with the anecdote and the study that make it true. Thirty seconds is enough, and the full lesson waits right behind for whoever wants the whole reasoning.
Q.02What exactly is calibration?
A decision maker is well calibrated when the things they announce at 70% happen about 70% of the time. It is independent of being right often: you can be very knowledgeable and very badly calibrated, saying 95% for things that happen two times out of three. Calibration is the rarest and most transferable judgment skill, because it is about how you dose confidence, not about a domain. Level 3 of the course is devoted to it entirely.
Q.03What is contrarian thinking?
It is not being against the crowd on principle, which still amounts to letting the crowd decide. It is knowing when the consensus sees right, and when it is wrong. Peter Thiel puts it in a single question: what important truth do very few people agree with you on? A useful contrarian follows the majority most of the time, and departs from it at the precise moment it is wrong, with reasons that can be checked before the outcome, not told afterwards.
Q.04Doesn't an AI forecast better than a human?
On knowledge and speed, by a mile. But a language model returns the consensus of everything that has been written: it is massively reasonable, rarely contrarian at the right moment. And the value of a decision plays out mostly when common thinking is wrong. That is exactly the ground Percentyl trains, and that is why the ability to depart from consensus with good reasons becomes more precious as reasoning becomes free.
Q.05What do I get out of answering every day?
One more true thing, and a streak. The question of the day makes no points: it lights a streak that counts the days in a row, it earns badges awarded by the database and never declared, and it leads to the lesson it comes from. A streak freeze is earned every ten days and covers one missed day, because regularity counts more than perfection.
Q.06Can judgment really be trained?
Yes, and it is measured. In the geopolitical forecasting tournaments of the 2010s, one hour of calibration training durably reduced participants' error, and the performance of the same forecasters persisted from one year to the next: so it was not luck. Philip Tetlock identifies the best predictor as not intelligence, but the habit of updating one's beliefs, which weighs about three times more. That habit is what the question of the day manufactures, one day at a time.
Q.07Is Percentyl gambling?
No, and it is structural: no stake, no purchasable currency, no money won, no investment advice. Badges and streaks are fictional units, not transferable. What you win here is one more true thing and the right to bring it up at lunch.
Q.08Am I going to get it wrong often?
At first, yes, and that is the point: a question everyone knows the answer to teaches nobody anything. The questions come from work where the intuitive answer is precisely the wrong one, because that is where documented biases live. Getting it wrong takes three seconds, the correction arrives in the same second, with the story that makes it memorable. None of this is public: your profile never shows what you answered to a given question.
Q.09Is the service free, and what is the business model?
The application is free and will stay free: one question a day, the contrarian thinking course in twenty-six lessons, the exam, the certificate and the public profile. Premium services will come later, around the community. No ads, no data selling, no financial advice.
Percentyl · judgment can be trained
Thirty seconds. Then start again tomorrow.
Free. One question a day, the contrarian thinking course included, a certificate you earn. The question of the day is waiting at the top of this page.
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