Alternative names for argumentum ad populum Informal Logical Fallacy.

When the claim that most or many people in general or of a particular group accept a belief as true is presented as evidence for the claim. Accepting another person's belief, or many people's beliefs, without demanding evidence as to why that person accepts the belief, is lazy thinking and a dangerous way to accept information.

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She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre