Which fallacy is the result of begging the question, i.e., assuming the same thing one wants to prove?

Which fallacy is the result of begging the question, i.e., assuming the same thing one wants to prove?

• A. Petitio principii
• B. Dictionary simpliciter
• C. Circulus in demonstrando
• D. Ad logicam

Answer: (A)

Begging the question means the argument assumes what it is trying to prove; it uses the conclusion as part of its own justification, giving no independent support. This is exactly what petitio principii describes—the circular move of presupposing the very point at issue. For example, saying “This drug works because it cures people; it cures people, therefore it works” treats the cure as proof of its own effectiveness, which is circular. The term petitio principii is the standard label for that kind of reasoning. The other terms describe related ideas: circu lus in demonstrando is a more explicit form of circular demonstration, while ad logicam and other labels refer to different fallacies and do not match the notion of presupposing the conclusion.

Begging the question means the argument assumes what it is trying to prove; it uses the conclusion as part of its own justification, giving no independent support. This is exactly what petitio principii describes—the circular move of presupposing the very point at issue. For example, saying “This drug works because it cures people; it cures people, therefore it works” treats the cure as proof of its own effectiveness, which is circular. The term petitio principii is the standard label for that kind of reasoning. The other terms describe related ideas: circu lus in demonstrando is a more explicit form of circular demonstration, while ad logicam and other labels refer to different fallacies and do not match the notion of presupposing the conclusion.