Course
How a mind decides what is true
Trace where a belief comes from, what a count can hide, what makes a reason reach its claim, and how a belief with a size moves when a clue arrives.
The shape of it
15 lessons
About 72 minutes in total. Your progress is kept on this device — no account, nothing sent anywhere.
Course complete
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The lessons
Where a belief comes from
4 lessons · about 20 min01Said is not checked
Tell apart a claim somebody said from a claim somebody checked, and spot what repeating does.
About 5 min
02The fast guess comes first
Spot the question that looks easy and is not, and say what the feeling of knowing is made of.
About 5 min
03Wanting it true weighs in
Tell apart 'can I believe this?' from 'must I believe this?', and spot which one a reader is asking.
About 5 min
04Sure is a feeling
Work out how often people who say they are sure turn out to be right, and where the gap is widest.
About 5 min
What a count can hide
4 lessons · about 19 min05A small count swings
Work out why a small group gives the wildest results, and spot a claim that rests on a few.
About 5 min
06Who got counted
Spot the gate between the world and the number, and name who never made it into the count.
About 5 min
07Together is not because
Tell apart two things that rise together from one causing the other, and say what a test changes.
About 5 min
08The number you skipped
Work out why a good test for a rare thing flags more healthy people than sick ones.
About 5 min
The shape of a reason
4 lessons · about 19 min09A reason joined to a claim
Tell apart a true reason from one that reaches its claim, and work out what a long chain costs.
About 5 min
10The person is not the reason
Spot when a claim is being held up by who said it or how many, and say what that tells you.
About 5 min
11What would prove it wrong
Tell apart a test that can only say yes from one that could say no, and spot a claim nothing can sink.
About 5 min
12Twenty tries and one shown
Work out how many tries pass by chance alone, and ask where the ones that failed went.
About 5 min
Moving the number
3 lessons · about 14 min13A belief has a size
Work out how far a clue moves a belief, and why a belief at the ends cannot move at all.
About 5 min
14Changing your mind is a skill
Score a forecast with a number in it, and tell apart the two styles of forecaster.
About 5 min
15A post, taken apart
Take one viral post apart with every tool in the course, and say where the number ends.
About 5 min