Bregman systematically dismantles the popular notion that humans are naturally evil by reexamining famous cases like the real-life Lord of the Flies incident, where children actually demonstrated remarkable cooperation rather than descending into savagery. He shows how many of our beliefs about human nature are based on misinterpreted or poorly designed studies.

The author presents compelling evidence that humans evolved to be cooperative, demonstrating how our species' success largely depends on our ability to work together and trust one another. This cooperative instinct, rather than competitive drive, has been key to our survival and development throughout history.

Bregman illustrates how our negative assumptions about human nature have created self-fulfilling prophecies in our institutions, from education to governance. He argues that by changing these assumptions, we can design better systems that bring out the best in people rather than the worst.