Steven Pinker on Common Knowledge, Rationality, and Social Coordination

The Concept of Common Knowledge

• 💡 Common knowledge is defined not just as widely shared information, but as knowledge that everyone knows that everyone else knows, recursively.
• 🎯 This concept is crucial for understanding how societies function, enabling conventions, social relationships, and collective actions.
• 🔑 Examples range from driving rules and respecting currency to informal social bonds and cooperative endeavors.

Common Knowledge in Communication and Social Interaction

• 🧠 Language often relies on indirect communication, using euphemisms and innuendo, because the intended meaning is common knowledge.
• 💬 The ability to understand these nuances depends on recognizing shared knowledge of intentions and social contexts.
• 🎭 Social relationships, like friendship or authority, are ratified by the common knowledge that both parties recognize their existence.

Logic Puzzles and Rational Agreement

• 🧩 The