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Predictably Irrational
The Hidden Forces That Shape Our Decisions
- Read in 15 minutes
- Audio & text available
- Contains 10 key ideas

Synopsis
Predictably Irrational (2010) explains the fundamentally irrational ways we behave every day. Why do we decide to diet and then give it up as soon as we see a tasty dessert? Why would your mother be offended if you tried to pay her for a Sunday meal she lovingly prepared? Why is pain medication more effective when the patient thinks it is more expensive? The reasons and remedies for these and other irrationalities are explored and explained with studies and anecdotes.
Key idea 1 of 10
To appraise things, we compare them to others.
Are you single? Here’s a surprising tip on how to attract potential dating partners at a club: bring along a friend who looks similar to you, only is slightly less attractive. This will greatly increase your chances of success.
Why?
Our minds are fundamentally wired to look for comparisons. What’s more, we tend to do this in the laziest way possible: by using the easiest comparisons around.
By showing up at a bar with a slightly less attractive version of yourself, you’re giving your potential dating partners an easy comparison. Instead of going to the trouble of comparing lots of different-looking people, they can clearly see that you are preferable to your friend. Since you won this easy contest and other comparisons are harder to make, you will probably be seen as the cutest person at the club. Congratulations! Just don’t tell your friend why you’ve invited them out.
The same tendency to compare applies to prices of products, and many marketers take advantage of this by introducing expensive “decoy products” that make other things seem cheaper by comparison. For example, some savvy restaurants will deliberately overprice the most expensive item on their menu, so customers will then feel the second most expensive item is relatively cheaper and wind up ordering it.
Though comparing helps us make decisions, it can also make us miserable. Constantly comparing your salary, clothes or car to others’ will leave you envious and in a state of perpetual displeasure with what you have. After selling his Porsche Boxster, James Hong, cofounder of hotornot.com, said:
“I don’t want to live the life of a Boxster, because when you get a Boxster you wish you had a 911, and you know what people who have 911s wish they had? They wish they had a Ferrari.”
Key ideas in this title
- To appraise things, we compare them to others.
- When we’re offered something for free, our rational thinking goes out the window.
- The first price number we hear affects what we are willing to pay later.
- We overvalue what we own.
- Our experiences are shaped by our expectations.
- People’s responses to your requests depend on whether they fall under social or market norms.
- People are prone to dishonesty, but not wildly so.
- Dr. Jekyll sets our rational long-term goals, but we must fight Mr. Hyde’s irrationality to reach them.
- People are obsessed with keeping their options open, even when it hurts them in the long run.
- Final summary