Also Known as: Circular Reasoning, Reasoning in a Circle, Petitio Principii, Vicious Circle, Circulus in Probando, Circular Argument.
Begging the Question is a fallacy in which the premises include the claim that the conclusion is true or (directly or indirectly) assume that the conclusion is true. This sort of "reasoning" typically has the following form:
The truth of the conclusion is assumed by the premises. Often, the conclusion is simply restated in the premises in a slightly different form. In more difficult cases, the premise is a consequence of the conclusion.
This sort of "reasoning" is fallacious because simply assuming that the conclusion is true (directly or indirectly) in the premises does not constitute evidence for that conclusion. Obviously, simply assuming a claim is true does not serve as evidence for that claim. This is especially clear in particularly blatant cases: "c is true. The evidence for this claim is that c is true."
Some cases of question begging are fairly blatant, while others can be extremely subtle.
Bill: "God must exist."
Jill: "How do you know."
Bill: "Because the Bible says so."
Jill: "Why should I believe the Bible?"
Bill: "Because the Bible was written by God."
"If such actions were not illegal, then they would not be prohibited by the law."
"The belief in God is universal. After all, everyone believes in God."
Interviewer: "Your resume looks impressive but I need another reference."
Bill: "Jill can give me a good reference."
Interviewer: "Good. But how do I know that Jill is trustworthy?"
Bill: "Certainly. I can vouch for her."
Since I'm not lying, it follows that I'm telling the truth.
We know that God exists, since the Bible says God exists. What the Bible says must be true, since God wrote it and
God never lies.
Here, we must agree that God exists in order to believe that God wrote the Bible.
Show that in order to believe that the premises are true we must already agree that the conclusion is true.