DEFECTIVE BY DESIGN : The Stupid History of The Science of Measuring Intelligence

Everything you think you know about intelligence is wrong.

Growth mindset? Effect sizes near zero. Grit? Just conscientiousness with better PR. The Mozart Effect? Your kid got no smarter from those CDs. IQ tests? Created to help struggling students, weaponized to sterilize 70,000 Americans.

For 120 years, intelligence research has followed the same pattern: promising science, corrupted by premature application, oversold to a public desperate for answers. Alfred Binet created a simple test to identify Parisian schoolchildren who needed help. Within decades, it justified forced sterilizations, immigration restrictions, and segregated schools. The Supreme Court approved it all.

The disasters didn’t stop there. Lewis Terman spent 35 years tracking gifted children who grew up disappointingly normal. The U.S. Army tested 1.7 million soldiers and proved only that the tests were garbage. Arthur Jensen started a 50-year scientific war with one paper. Psychologists built elaborate theories about multiple intelligences that couldn’t survive basic scrutiny.

Then came the replication crisis. Suddenly, psychology’s greatest hits were crumbling. Priming studies? Couldn’t replicate. Social psychology interventions? Vanishing effect sizes. The science was broken, but the self-help books kept selling.

This book tells the whole story. From Binet’s good intentions to modern AI’s fundamental confusions about what intelligence even means. From eugenics to educational fads to the failed search for intelligence genes. It’s darkly funny because the alternative is just depressing. It treats researchers as humans trying to answer genuinely difficult questions while showing, with uncomfortable precision, how consistently they got it wrong.

Who needs to read this? Anyone who’s worried about their IQ or their kid’s test scores. Teachers spending budgets on interventions that don’t work. Parents considering expensive “brain training” programs. Anyone who’s been told that success is all about mindset or grit or emotional intelligence. People who want to understand how science goes wrong, not just in psychology but everywhere.

You’ll finish this book knowing what intelligence research has actually discovered versus what it’s claimed to discover. You’ll understand why the confident proclamations keep failing. And you’ll recognize the warning signs when the next miracle intervention promises to transform education, unlock potential, or finally explain what makes us smart.

This is the book popular psychology doesn’t want you to read. It’s what happens when someone actually checks the footnotes, reads the replication studies, and follows the money. It’s for people who can handle uncomfortable truths and prefer brutal honesty to comforting oversimplifications.

The history is real. The science is verified. The conclusions are realistic, not inspirational.

And that’s exactly the point.