Appeal to popularity (argumentum ad populum)

Biological Parallel

Starlings in murmurations follow nearest neighbors' flight direction without independent assessment of threats. This 'copy the majority' rule creates rapid, coordinated evasion—even when the initial turn was a false alarm. The heuristic works because, ancestrally, if most of your group is fleeing, the metabolic cost of independent verification exceeds the cost of unnecessary flight. Popularity appeals exploit this social proof instinct: majority behavior feels like evidence because it usually was.