Why do some ideas catch fire while others fizzle out? Why can a single tweet spark outrage, or a secret topple a regime? In his new book, When Everyone Knows That Everyone Knows…, world-renowned cognitive scientist Steven Pinker argues that the answers lie in one of the most powerful—and least understood—forces shaping human society: common knowledge.

It’s the invisible glue that binds communities and the spark that ignites revolutions. It’s why we laugh at the same jokes, follow social norms, and occasionally, descend into chaos. “We don’t just think,” Pinker explains, “we think about what others think we think.”

Drawing on decades of research in psychology, linguistics, and game theory, Pinker takes readers on a captivating journey into the collective mind. From social media pile-ons and financial bubbles to acts of solidarity and diplomacy, When Everyone Knows That Everyone Knows… explores how our shared awareness—what we know that others know—shapes everything from politics and culture to our most intimate relationships.

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Why This Book Speaks to Now

At a time of viral misinformation, digital echo chambers, and growing polarization, Pinker offers a timely framework for understanding why we behave the way we do—together.

• Reveals how shared knowledge drives social movements, revolutions, and even cancel culture
• Unpacks the psychological feedback loops behind outrage, cooperation, and trust
• Connects the science of cognition with the realities of modern life—from boardrooms to group chats
• Challenges readers to rethink what it really means to “know” something in the age of social media

When Everyone Knows That Everyone Knows… is both a scientific revelation and a social mirror—one that helps us see how deeply our lives are entwined with the perceptions of others.

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A Voice the World Listens To

Hailed by TIME as one of the world’s most influential thinkers, Steven Pinker has long been celebrated for his ability to turn complex science into stories that change how we see ourselves. His bestselling works—including The Better Angels of Our Nature, Enlightenment Now, and Rationality—have transformed public understanding of human progress and the mind’s inner workings.

Pinker is the Johnstone Professor of Psychology at Harvard University, a two-time Pulitzer Prize finalist, and an elected member of the National Academy of Sciences. Across twelve books, his central mission has remained the same: to show that understanding how we think is key to improving how we live.

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The Big Idea

At its heart, When Everyone Knows That Everyone Knows… is about connection—how our minds are never truly alone. Every decision, every reaction, every social moment is part of a vast, recursive web of awareness.

As Pinker writes, “Civilization depends not just on knowledge, but on knowing what others know. It’s how trust begins—and how it can collapse.”

With trademark wit, clarity, and intellectual rigor, Steven Pinker once again challenges readers to see the world—and themselves—through a more reflective, deeply human lens.

When Everyone Knows That Everyone Knows… is available now from Penguin Random House.