Predictably Irrational: Why We’re Not As Smart As We Think

I recently finished reading Predictably Irrational by Dan Ariely, and I haven’t stopped thinking about it since. It was fascinating, unsettling, and—if I’m honest—a bit of a wake-up call.
We like to think of ourselves as rational beings. We make decisions based on logic, evidence, and careful consideration… don’t we?
Apparently not.
Ariely, a behavioural economist, uses dozens of experiments to show that not only are we irrational, but our irrationality is predictable. That is, we tend to make the same mistakes over and over again—and often in exactly the ways you’d expect once you understand the patterns.
The Invisible Strings That Pull Us
Some of the examples in the book are almost laughably simple. Like the way we gravitate toward anything labelled “free,” even when it’s worse value than another option. Or how companies shape our choices by offering deliberately bad options so that the “middle” one seems like a good deal. We don’t compare things in isolation; we compare them to what’s next to them.
One of the most eye-opening chapters explored how our expectations shape our experiences. In one experiment, people were given a drink that tasted awful—but told it was an expensive energy booster. Many swore it helped them focus. Our minds, it turns out, are easily persuaded—not by truth, but by suggestion.
And that, really, is the point. We are far less in control than we like to think.
A Mirror for Our Moment
Reading Predictably Irrational in a post-COVID world only made its insights feel more urgent. The way people responded to vaccines, lockdowns, and government advice wasn’t always based on logic or science. It was driven by emotion, identity, group pressure, and distrust.
This isn’t a criticism of others—none of us are immune. We all carry biases. We all make snap judgments. We all resist information that doesn’t fit our worldview. COVID didn’t create irrationality; it simply exposed it.
And the same applies to our politics. Our beliefs feel reasoned and clear in our own heads, but they’re often rooted in emotion, tribal loyalty, or fear. We look for news that confirms what we already think. We believe the worst about those who disagree. And all the while, algorithms and advertisers are quietly nudging us further into echo chambers, because they understand what Ariely explains so well: we’re not rational thinkers—we’re predictably irrational ones.
So What Do We Do?
That’s the question Ariely doesn’t leave us hanging on. The aim of the book isn’t to make us feel foolish, but to help us become more aware. Once we see the patterns, we can begin to resist them. We can pause before making a purchase, stop and reflect before reacting, and become more curious about our own blind spots.
For me, this book was a call to humility. A reminder that I don’t always see things clearly. That others aren’t necessarily mad or bad when they disagree—they might just be shaped by different forces than I am. And that awareness is a powerful step toward better decisions, healthier conversations, and wiser leadership.
If you’re looking for a book that will challenge how you see yourself, your decisions, and the world around you—Predictably Irrational is well worth your time. Just be warned: once you’ve seen the strings, it’s hard to unsee them.