Common Knowledge

Common Knowledge is what everyone knows that everyone knows.

Is why coronations and executions are held in public – not so a crowd can see the new king or the hanged man, but so a crowd can see a crowd seeing the new king or the hanged man. Is why

• sitcoms have laugh tracks
• the Egyptian government fell in 2011 after a televised protest
• the Romanian government fell in 1989 after a televised protest in Palace Square

We are sheep. Our behaviour changes when we think others share our perspectives. It's not enough to notice the emperor has no clothes, but to be sure others noticed it too.