What Lilypads Teach Us About Faulty Thinking
Ever since I first read Thinking, Fast and Slow a few years ago, I’ve been fascinated by how our minds work and how often they trick us. Psychology, mental shortcuts, cognitive biases … it’s a rabbit hole I keep going back to. (Every now and then I re-read the book - here’s a summary if you’re curious.)
Books like The Art of Thinking Clearly have only deepened my interest. What amazes me is: our brains are powerful, but they’re also full of bugs. Sure, these shortcuts may have helped us survive back in the stoneage (versus the “saber tooth tigers”). But in today’s world, they often lead us astray.
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| Photo by Cheng Shi Song on Unsplash |
In this article, I want to share a few simple but eye-opening examples of how flawed our thinking can be.
Let’s start with lilypads.
Doubling Lilypads
Before we dive in, just one hint: for this exercise use the first answer that comes to your mind.
There is a lake with lilypads. At first there is just one plant on the lake, but they double every day. The lake is completely full with lilypads on day 20.
And now the question: when is the lake half-full?
… try to answer yourself …
Is it 10 days?
No.
Actually, it is 19 days. If the lake is full on day 20 and the lilypads double every day, then on day 19 it is half-full. Then it doubles and it is full on day 20.
But why does the answer 10 days come to mind so quickly? Our intuition misleads us, making 10 feel like half of 20.
Ball and Racket Pricing
In Thinking, Fast and Slow there is another example in that direction. Again, try to answer quickly.
A ball and a racket together cost $11. The racket costs $10 more than the ball.
And now the question: how much does the ball cost?
… try to answer yourself …
Is it $1?
No.
Again the intuitive answer is wrong. If the ball would cost $1 then the racket would cost $10 more than the ball → $11. The ball and the racket together would then cost $12.
The correct answer is 0.50 $.
Conclusion
Both examples show how easily we let ourself trick us by our intuition. And yes, in many situation intuitive answers are great (we can’t always fire up our slow thinking). However, if decisions get important, give yourself more time and ask twice if the quickest answer coming to your mind is actually correct.