Critical thinking
Most of what reaches you every day is somebody's claim: an ad, a post, a doctor's pamphlet, a boss, a news story, a relative at dinner. Nobody can check everything, so the skill is knowing which claims to trust, which to test, and how. People who never learn it spend their money, their votes and their health on other people's say-so.
By the end you will be able to...
- Tell a claim from its evidence.
- Spot the standard ways an argument cheats.
- Know what a number can and cannot say.
- Notice when a story is doing the thinking for you.
- Change your mind in public without shame.
- Read a hard text without an intermediary telling you what it means.
A claim is not its evidence
A stage magician tests faith healers, spoon benders and astrologers by setting up fair tests, not by arguing. Watch how each test is built.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
Before you can weigh anything, you have to see that "this works" and "here is how we know" are two different things. Most people hear the first and assume the second.
How this reaches you
Supplements, miracle cleaners, "studies show", the phone call that says your car warranty is expiring. Each one is a claim asking for your money before it shows its evidence.
The shipowner who believed his ship was sound. A short, sharp argument that believing without evidence is a wrong done to other people.
Astrology and astronomy started as one thing. Sagan shows the moment they split: Kepler threw away his own beautiful theory because eight minutes of arc did not fit the data.
Do this week
Pick one claim you heard this week. Write the claim on one line and its evidence on the next. If the second line is empty, that is your answer.
Who teaches this unit
- James Randi, stage magician and investigator. Exposed faith healer Peter Popoff and spoon bender Uri Geller with demonstrations, not arguments.
- Carl Sagan, astronomer. Worked on the Viking and Voyager missions; wrote the baloney detection kit.
- W. K. Clifford, mathematician. A geometer whose 1877 essay on belief is still argued over.
How an argument cheats
Schopenhauer wrote down, plainly and a little cynically, the tricks people use to win an argument when they are wrong. Stratagems 11 to 38 follow in the next parts.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
The tricks are old and there are not many of them. Once you can name them, they stop working on you, and you stop using them by accident.
How this reaches you
Sales pitches, arguments at work, comment threads, family fights, political ads. The same few moves show up in all of them.
A short essay with an exact distinction: a liar cares about the truth enough to hide it; a bullshitter does not care either way.
Find it at a libraryDo this week
Watch any panel show or comment thread for ten minutes and name three of Schopenhauer's stratagems by number when you catch them.
Who teaches this unit
- Arthur Schopenhauer, philosopher. Catalogued the tricks of dishonest argument so people could see them coming.
- Harry Frankfurt, philosopher. Gave the exact difference between lying and not caring about the truth.
What a number can and cannot say
A doctor who worked in Mozambique shows that what most educated people believe about the world is decades out of date, and how one chart fixes it.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
Numbers sound like the end of an argument. They are usually the start of one: who counted, what they counted, and compared with what.
How this reaches you
Interest rates, "cuts your risk by half", crime up 200 percent, a raise that is smaller than prices went up. Your money and your health decisions come wrapped in numbers.
Nine minutes on what one machine did for his mother, and what energy numbers mean in a real home.
The hour-long version, for when the talk hooks you.
When are we allowed to believe beyond what we have seen?
Do this week
Find one percentage in today's news. Ask three questions of it: a percent of what, compared with what, and who counted.
Who teaches this unit
- Hans Rosling, physician and statistician. Practised medicine in Mozambique, then built Gapminder to show the world as the numbers say it is.
- Darrell Huff, journalist. Wrote the most-read book on how statistics mislead.
- W. K. Clifford, mathematician. A geometer whose 1877 essay on belief is still argued over.
When the story does the thinking
A teacher of forty years on what happens to thinking when information arrives faster than anyone can judge it. Said in 1990.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
A good story feels true because it is well told, not because it is true. Whole countries have bet everything on a story everybody around them believed.
How this reaches you
Every bubble works like this: tulips in 1637, houses in 2007, whatever is next. So do feeds that keep you angry. If everyone around you is sure, that is the moment to check.
How a whole country came to trade houses for flower bulbs, told by a writer who saw the same thing happen again in his own time.
Do this week
Think of one thing "everybody knows" in your circle. Write down where you first heard it and whether you ever saw it for yourself.
Who teaches this unit
- Neil Postman, teacher and media critic. Forty years in the classroom; saw what television would do to public argument.
- Charles Mackay, journalist. Chronicled the bubbles and manias of three centuries in 1841.
Changing your mind without shame
A mathematician stands at Auschwitz and says what happens when people believe they have absolute knowledge. The most quoted ending in television science.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
Being wrong is normal. Staying wrong to save face is what does the damage. The people we most admire for thinking clearly are the ones who said "I was wrong" out loud.
How this reaches you
At work, at home, in a family argument that has run for years. The person who can say "I hadn't thought of that" ends up trusted.
Why even a wrong opinion should be heard: the person who only knows their own side of a case knows little even of that.
Do this week
Pick one opinion you hold firmly. Write the strongest case against it you can, as if you believed it. Show it to someone who does believe it and ask if you got it right.
Who teaches this unit
- Jacob Bronowski, mathematician and historian of science. A working scientist who made The Ascent of Man.
- John Stuart Mill, philosopher and economist. Wrote the case for free thought and discussion that is still quoted in courts.
Find out for yourself
A Nobel physicist on his father, the bird whose name tells you nothing about the bird, and why he would rather not know than be told.
Make it set
Five partials from this unit are floating in a supercooled liquid. Everything is here, and nothing has set. One more piece is the nucleation point. Pick it and watch what happens. There is no score.
Now say it another way
You have learned it when you can say it in your own words. Write it the way you would tell a friend.
This stays on this device. Nobody grades it.More: why it matters, what else to watch, read and do, who teaches it
Why it matters
Knowing the name of a thing is not knowing the thing. Every summary is someone's choice of what to leave out, so the habit worth having is going to the source.
How this reaches you
Your lease, your insurance policy, a law people are fighting about, a study a headline is quoting. The original is usually shorter and plainer than people assume.
Ask him why magnets push each other apart and watch him refuse to give you an easy answer that isn't true.
Do this week
Pick a short hard text you have only heard about: your lease, a founding document, a law in the news. Read it yourself first, then one summary, and write down where they differ.
Who teaches this unit
- Richard Feynman, physicist. Nobel prize; found the cause of the Challenger disaster with a glass of ice water.
- Mortimer Adler, philosopher and teacher. Ran the Great Books programme and taught reading as a skill.