Idioms, Fallacies, and Paradoxes

Argumentum Ad Populum

In argumentation theory, an argumentum ad populum is a fallacious argument that conclused that a proposition is true or good solely because many or most people believe it: "If many believe so, it is so."

This type of argument is known by many names, including appeal to the masses, appeal to belief, appeal to the majority, appeal to democracy, appeal to popularity, argument by consensus, consensus fallacy, authority of the many, bandwagon fallacy, vox populi, and in Latin as argumentum ad numerum, fickle crowd syndrome, and consensus gentium.

It is also the basis of a number of social phenomena, including communal reinforcement and the bandwagon effect. The chinese proverb "three men make a tiger" concern the same idea.