When Everyone Knows That Everyone Knows

Pinker takes a genuinely slippery concept from game theory—the difference between everyone privately knowing something and everyone knowing that everyone knows it—and uses it to explain why a euphemism can function as plausible deniability, why a scandal doesn't detonate until it's aired publicly, and why money and social status depend on shared belief rather than private conviction. The examples range from the emperor's new clothes to central bank signaling, and the writing is characteristically lucid. The trade-off is that common knowledge itself stays somewhat impressionistic as a unifying idea; the book is stronger as a tour of vivid applications than as a rigorous account of the mechanism generating them, leaving some of its biggest claims about power and coordination feeling asserted rather than demonstrated.