Leaders love the feel of a unanimous “yes” because it signals cohesion and saves time, yet that same harmony can mute the dissent that would otherwise surface real risk. A well-documented bias called false-consensus leads people to assume their own view is already shared, so they suppress objections rather than voice them. When a decision deadline feels tight, the cost of one more dissenting question looks higher than the cost of being wrong, and the group defaults to speed over scrutiny.

The 1962 Cuban Missile Crisis is the case researchers point to when they want an antidote to groupthink rather than an example of it. Kennedy's Executive Committee broke into competing subgroups to independently evaluate a naval blockade against a surprise air strike, and Kennedy himself stepped out of several meetings so aides would argue more freely without deferring to the president in the room. Robert Kennedy's objection to a surprise attack — that it would make the United States look like the aggressor in a “Pearl Harbor in reverse” — pulled the group back from the military's preferred first-strike option and toward the slower, verifiable path of a blockade.

The quarantine that followed was still a gamble, but it was a scrutinized one: Kennedy and his team modeled the Soviet response, kept a diplomatic back channel open, and left room to de-escalate that a surprise strike would have foreclosed entirely. Modern teams that skip the equivalent moves — splitting into independent subgroups, explicitly assigning someone to argue the other side, stepping back so juniors will speak freely — often mistake a quiet room for agreement. They discover the dissent was real, just unspoken, only after the decision fails and the costly reversal begins.