In his book Rational Ritual, the political scientist Michael Chwe illustrates common knowledge using email.11 If you invite your friends to a party using the “To” and “Cc” fields, the party will be common knowledge—because every recipient can see every other recipient. But if you invite your guests using the “Bcc” field, even though each recipient individually will know about the party, it won’t be common knowledge. We might refer to information distributed this way, in the “Bcc” style, as closeted rather than common. Whether information is common or closeted can make a world of difference. In
...more
