Key Takeaways
- Common knowledge, where everyone knows everyone knows, is the secret engine of social coordination.
- It crucially empowers collective action and profoundly shapes financial markets and personal bonds.
- Yet, the strategic suppression of common knowledge is essential for maintaining social harmony and fictions.
Deep Dives
Coordination Catalyst
- Pinker defines common knowledge as shared awareness, where everyone knows others share it, driving coordination from simple meet-ups to international diplomacy.
- He illustrates this with "The Emperor's New Clothes," where a child's public declaration transformed private knowledge into common knowledge, enabling collective action.
Strategic Impact
- Autocrats fear common knowledge of dissent; public protests, like blank signs in Russia, signify shared opposition and empower collective action.
- In financial markets, common knowledge underpins speculative bubbles, as investors predict what others will predict, as seen in Keynes' beauty contest analogy.
Societal Foundations
- Common knowledge also shapes personal relationships, using subtle signals like eye contact or innuendo to convey understanding and maintain social fictions.
- Unwritten social norms, from individual courtesy to international agreements, rely on common acceptance but are vulnerable if openly flouted or discussed, highlighting their fragility.