Think Again: The Power of Knowing What You Don't Know

I did not like Grant's previous book, Originals, very much. So I didn't have very high expectations for this one. Nevertheless, the subject matters to me, and this book has received some good ratings, so I thought I'd give it a shot. It was good. I learned a lot of things that I didn't know. Some things I thought I knew I learned were wrong. This is what I love in good books - they challenge your beliefs. They make you think. Rethink. My critique of this book is that the examples feel too drawn out. This made the book cumbersome to read because I was bored sometimes. It was like a rollercoaster of thinking. Either way, I got through it, and I'm happy I did.

4 min read

Summary of Key Points

  • Being able to rethink and unlearn is an incredibly important skill.
    • We need to question our assumptions.
  • In order to become better at this, we need to think more like scientists. We need to think in terms of experiments and use the scientific method.
    • Scientist mode: questioning our own beliefs. Assuming first that we are wrong and trying to confirm that hypothesis, not the other way around. Then adjusting our views accordingly.
    • Be humble about what you think you know.
      • It starts with humility about what we don't know. This allows us to doubt our convictions, such that we can discover new evidence. This continues the cycle by affirming that we don't know everything. It's a learning cycle that benefits you greatly.
      • You want confidence and humility. Believing in yourself but having uncertainty about your tools. This is the golden zone between armchair quarterback syndrome and imposter syndrome.
        • Imposter syndrome can motivate us to work harder. We think we have something to prove, so we work hard to do it.
        • Feeling like an imposter makes us feel like a beginner, and therefore we question assumptions.
        • Your doubts are indicators that you need to upgrade your tools.
  • You can't learn what you think you know.
  • Base your identity on your values, not your beliefs. This gives you the freedom to update your beliefs.
  • Fight confirmation bias by seeking evidence that opposes your views.
  • We usually think we are better than we actually are. This is called The Dunning-Kruger Effect. Try to avoid it.
  • Embrace being wrong. You just learned something.
  • You can learn something from anyone you meet. Everyone knows something you don't.
  • Try to build a network of people who can (and will) challenge your views.
  • Stay open to rethinking your 10-year plan. You change as a person. You can't be sure that you want the same things that far in the future.
  • Question best practices more often. Sure, they're there for a reason, but how do you know that it's the best possible approach?
  • When debating...
    • Bringing too many arguments dilutes them. The chain is only as strong as the weakest link.
      • Develop your best arguments rather than continuing to spew new ones.
    • Be open. Ask questions. Give credit. Find common ground.
      • Listen more.
      • Try to ask how they originally formed their opinion.
    • Consider the strongest version of your opponent's argument. This is called steel manning. The reverse is straw-manning.
    • People are more likely to convince themselves than you are to convince them. Ask questions to make them ponder.
    • Strong opinions, weakly held might not be the best approach. Being on either end of the confidence spectrum makes you less credible and less persuasive. It's better to be moderately confident; you believe in yourself because your reasons are well-thought-out, but you're open to the possibility that you might be wrong.
    • Try to find common ground and acknowledge it. This shows that you're willing to negotiate.

The purpose of learning isn’t to affirm our beliefs; it’s to evolve our beliefs.

Highlights & Notes


First instinct fallacy

When taking a test, we more often change our answers from wrong to right, although it is common advice to rely on your instincts.

Have you heard the story about the frog put into boiling water? That it would simply jump out immediately again. But if we put it into cold water which we slowly heat up, it wouldn't register the changes and die a slow death - it would never jump out.

Well, turns out that this story is false. It's actually the other way around. The frog is more likely to perish if put into boiling water because it might take damage from that. And if put into water that is heating up, it'll jump out when the water becomes uncomfortable.

Progress is impossible without change; and those who cannot change their minds cannot change anything.

— George Bernard Shaw

Chapter 1: A Preacher, a Prosecutor, a Politician, and a Scientist Walk into Your Mind

Mental horsepower doesn’t guarantee mental dexterity. No matter how much brainpower you have, if you lack the motivation to change your mind, you’ll miss many occasions to think again. Research reveals that the higher you score on an IQ test, the more likely you are to fall for stereotypes, because you’re faster at recognizing patterns. And recent experiments suggest that the smarter you are, the more you might struggle to update your beliefs.

Hilarious. The faster you run, the harder you fall. Smart does not imply wise.

Desirability Bias

Seeing what you want to see is called Desirability bias. We allow our preferences to cloud our judgment.

My favorite bias is the “I’m not biased” bias, in which people believe they’re more objective than others. It turns out that smart people are more likely to fall into this trap. The brighter you are, the harder it can be to see your own limitations. Being good at thinking can make you worse at rethinking.

The smarter you are the harder it is to question your beliefs.

The purpose of learning isn’t to affirm our beliefs; it’s to evolve our beliefs.

Chapter 2: The Armchair Quarterback and the Imposter

Ignorance more frequently begets confidence than does knowledge.

— Charles Darwin

The Dunning-Kruger Effect "It’s when we lack competence that we’re most likely to be brimming with overconfidence."

As Dunning quips, “The first rule of the Dunning-Kruger club is you don’t know you’re a member of the Dunning-Kruger club.”

Coined by David Dunning and Justin Kruger.

Chapter 3: The Joy of Being Wrong

“People who are right a lot listen a lot, and they change their mind a lot, if you don’t change your mind frequently, you’re going to be wrong a lot.”

— Jeff Bezos

Chapter 6: Bad Blood on the Diamond

The Ship of Theseus Paradox

"In ancient Greece, Plutarch wrote of a wooden ship that Theseus sailed from Crete to Athens. To preserve the ship, as its old planks decayed, Athenians would replace them with new wood. Eventually all the planks had been replaced. It looked like the same ship, but none of its parts was the same. Was it still the same ship? Later, philosophers added a wrinkle: if you collected all the original planks and fashioned them into a ship, would that be the same ship?"

Is an object that has had all of its parts replaced still the same object? And what if all the original parts were reassembled - is it the same object, then?

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