The Art of Thinking Clearly

Rolf Dobelli

Rating: 7.5/10.0

99 chapters, each one describes a logical fallacy. This book is worth reading because our “squishy human brains” (as Professor Gregor Richards would say) are not designed for the modern world. For hundreds of thousands of years, our brains evolved to fit the needs of hunter-gatherers. Then 10,000 years ago we started farming. And now we have cruise missiles and TikTok rizz parties. So it’s probably a good idea to try and better equip our brains to deal with the present day world.

I don’t have much else to say. Here are some interesting fallacies. Just some food for thought:

• Confirmation bias: We all know about it, but how often do you actively fight it? Write down your beliefs and predictions and revisit them in the future to see how wrong you are.


• Gambler’s fallacy: “The roulette was red 5 times in a row now, it must be black soon!” Past results don’t change the probability of independent events. This is easy to spot at the casino, but less obvious in real life. I marked assignments as a teaching assistant last term and fell victim to gambler’s fallacy. A string of high scoring assignments in a row cause me to question whether I’m being too lenient, so I might have marked the next one harder. And vice versa with a string of low scoring assignments convincing me to be more forgiving. Similarly, consider a banker reviewing mortgage applications or an umpire calling balls and strikes.


• Hot hand fallacy: The opposite of the gambler’s fallacy — a sleuth of the same result does not mean the probability of that event is higher*. To differentiate between gambler’s fallacy and hot hand, let’s say I flip a coin 10 times and get 8 heads. Gambler’s fallacy says the next flip must be tails. Hot hand fallacy says the coin must be weighted. In the real world, when the economy is booming, people often make decisions as if economic conditions will continue to do well (i.e. buy stocks, take out a loan). On the other hand, those who fall victim to gambler’s fallacy believe there must be a recession soon and use confirmation bias to back their belief. On Wall Street, we call the former group “bulls” and the latter group “bears”.


• Social Loafing: In larger groups, people individually contribute less because less blame can be attributed to you as an individual. Conventional wisdom says this downside of big groups is offset because diversity of opinions leads to more informed decisions. Ironically, larger groups will collectively take larger risks, once again because each person shares a smaller piece of the blame.


• Wisdom of the Crowd: It’s hard to guess the number of jellybeans in a jar. But take the average of the guesses of 100 people, and you get astonishingly close. Therefore, “highest bidder” activities like auctions and initial public offerings (IPOs) are almost always overpriced.

Noteable Excerpt: “It’s okay to be envious—but only of the person you aspire to become.”

IRL Update (06/09/2024): For the first time in university, I am somewhat satisfied with my school-social-personal life balance. Knock on wood.

* Well, it might be. But you would use statistical analysis like hypothesis testing to confirm that.