Nudge

is, ignorance, on the part of all or most, about what other people think. We may follow a practice or a tradition not because we like it, or even think it defensible, but merely because we think that most other people like it. Many social practices persist for this reason, and a small shock, or nudge, can dislodge them.6 A dramatic example is communism in the former Soviet bloc, which lasted in part because people were unaware how many people despised the regime. Dramatic but less world-historical changes, rejecting long-standing practices, can often be produced by a nudge that starts a kind of bandwagon effect.