Not Born Yesterday: The Science of Who We Trust and What We Believe

This book completely flipped my understanding of why we believe what we do. Mercier presents a refreshing, optimistic take on human nature by arguing that we aren't just mindless sponges soaking up misinformation. Instead, he introduces the concept of "open vigilance," suggesting that our cognitive mechanisms are actually quite sophisticated at filtering out bunk. I found his analysis of why mass propaganda—even in Nazi Germany—often fails to change minds to be absolutely gripping. It challenges the common hysteria surrounding "fake news" by showing that people usually only accept messages that align with their pre-existing views. The writing is clear enough for a layperson while remaining deeply rooted in evolutionary biology. If you're tired of hearing how "sheep-like" society is, this is a must-read.

As someone who has always been skeptical of the "default to truth" theory, I found this to be an incredibly validating read. Mercier uses rigorous data to show that humans are naturally untrusting, not naturally gullible. The way he blends evolutionary history with modern examples of social media rumors is masterclass level. Personally, the most striking part was his explanation of "friction and flooding" in state censorship—it makes so much more sense than the idea of simple brainwashing. The book is optimistic without being naive, suggesting that we have the tools to navigate a world of misinformation if we just understand how our own skepticism works. It's one of those rare books that changes how you view every conversation you have. I've already recommended it to several colleagues in the psych department.

Picked this up because I was tired of the "everyone is stupid" narrative in modern non-fiction. Mercier’s work is a breath of fresh air. He explains that we have "open vigilance" mechanisms—like plausibility checking and reputation tracking—that keep us safe from most scams and lies. The idea that we are actually *too* skeptical sometimes is a fascinating flip on the usual discourse. I loved the breakdown of why some rumors spread like wildfire while others die out; it usually comes down to how much the information actually matters to our daily lives. The prose is engaging and the research feels cutting-edge. This is easily the most important book on human communication I’ve read in the last five years. Highly recommended for anyone interested in why we trust who we trust.

Ever wonder why people seem to fall for the most ridiculous internet rumors? Mercier’s distinction between intuitive and "reflective" beliefs explains this beautifully. He argues that most people don't actually act on the crazy things they claim to believe; it’s more like "mind candy" or a social signal for their in-group. To be fair, I felt he was a bit dismissive of the real-world harm some of these fringe beliefs cause, but his logic is hard to argue with. The chapter on how scammers use intentionally absurd emails to filter for the most vulnerable targets was a total lightbulb moment for me. It’s a dense read at times, but the unique perspective on trust and communication makes it worth the effort. I’ll be thinking about his arguments on mass persuasion for a long time.

Finally got around to reading this after hearing so much about it in skeptical circles. It’s a solid, well-reasoned look at why we aren't as easily misled as we fear. Mercier’s point that if we were truly gullible, we would have been wiped out by evolution long ago is a simple but powerful observation. I particularly enjoyed the sections on how we evaluate sources based on competence and shared interests rather than just blindly following authority figures. Look, it’s a bit academic in parts, and I think he oversimplifies the influence of demagogues, but the overall framework is incredibly helpful. It’s a great antidote to the constant doom-scrolling about the end of truth. We aren't born yesterday, and Mercier proves it through a very clever lens of cognitive science.

The premise is deceptively simple: we aren't the easy targets for manipulation that the media makes us out to be. Mercier argues that the real problem isn't that people are too trusting, but that we often have very specific, rational reasons for who we choose to listen to. I liked how he tackled the Pizzagate conspiracy, showing that while thousands of people talked about it online, only one person actually showed up with a gun. This suggests most "believers" didn't actually hold the belief as an intuitive reality. My only gripe is that the writing can be a bit dry in the middle chapters. However, the insights into how we use bad information for social gain are brilliant. It's an essential read for anyone trying to understand the current political climate.

After hearing Mercier on a podcast, I had to dive into the full text. He does a great job of debunking the myth that we’re all just a bunch of biases in a trench coat. Instead, he portrays humans as cautious information consumers who are quite difficult to move unless the argument is solid. I found the section on "reflective beliefs" particularly useful for understanding why people post crazy things on social media without actually changing their behavior. Not gonna lie, some of the evolutionary biology gets a bit technical, but he usually brings it back to a relatable example quickly. It's a very unique, data-driven defense of human intelligence that we desperately need right now. A bit repetitive toward the end, but the core thesis is rock solid.

While Mercier presents a compelling case against human gullibility, I couldn't shake the feeling that he was being a bit selective with his data. The evolutionary psychology behind our "open vigilance" mechanisms is fascinating, but the author often avoids confronting significant counterarguments like the sunk-cost fallacy or repetition bias. Frankly, it felt like he was cherry-picking studies to make his own contribution appear more revolutionary than it might actually be. There were several moments where I found myself asking, "But what about x?" only to find a vague dismissal in a footnote. It’s a thought-provoking essay, but it probably should have been either 30% longer to address these gaps or more humble in its scope. Still, it's a useful read for anyone in the cognitive science field.

Not what I expected, but interesting nonetheless. The book tries to prove that mass persuasion doesn't work, which is a bold claim in the age of Cambridge Analytica. While I appreciate the attempt to go against the grain, some of the historical examples felt a bit stretched to fit the narrative. For instance, his take on the Crusades as a rational choice for starving peasants was fascinating but felt like it ignored the massive religious and cultural pressures of the time. Truth is, the book is at its best when discussing individual cognitive mechanisms and at its weakest when trying to explain away large-scale social movements. It’s a fun, albeit occasionally annoying, intellectual exercise. If you like challenging your own biases, give it a go, but don't expect a perfect argument.

I really wanted to like this, but the author's tendency to tear down other researchers felt unnecessarily aggressive and, at times, a little dishonest. Mercier seems to depict accomplished experts as incompetent charlatans just because they disagree with his specific thesis on gullibility. As I progressed, I ironically lost trust in his ability to provide a charitable review of the literature. For example, when he argues that propaganda is ineffective, he almost entirely ignores the power of belief bias and confirmation bias. It’s a very frustrating reading experience because the core ideas are actually quite brilliant, but the execution feels like a series of missed opportunities to engage with the actual complexity of human reasoning. I’d recommend it only if you’re prepared to take every claim with a massive grain of salt.