Task: Sentence Expansion
Input (English): An appeal to popularity , also called argumentum ad populum ( Latin for " appeal to the people " ) , is a logical fallacy .
Output (English): In argumentation theory , an argumentum ad populum ( Latin for " argument to the people " ) is a fallacious argument that concludes that a proposition must be true because many or most people believe it , often concisely encapsulated as : " If many believe so , it is so . "