As a primate, you are quick to form groups and then feel as if you should defend those groups from the ill wishes of other groups. When groups get together to make a decision, an illusion of invulnerability can emerge in which everyone feels secure in the cohesion. You begin to rationalize other people’s ideas and don’t reconsider your own. You want to defend the group’s cohesion from all harm, so you suppress doubts, you don’t argue, you don’t offer alternatives—and since everyone is doing this, the leader of the group falsely assumes everyone is in agreement.
