A fallacy is a mistake in the logic of one’s thinking or communicating which leads to wrong conclusions. We as those who desire to be clear thinking and accurate about the properties of reality need to be familiar with fallacies as we are presented with them, in order to hone our ability to rightly appraise truth claims.
Definition: Begging the Question, or Circular Reasoning, occurs when the claim that is being argued for is assumed in one of the premises. In argumentation, one must move from premises that are known to a conclusion that is unknown. In a circular reasoning argument, the conclusion is dependent on the premises, as is proper, but the faulty premise’s truth is dependent on the conclusion being true. “Begging the Question” is sometimes used colloquially to mean, “raises the question,” but that is not the usage which I am describing here as a fallacy.
Examples: The Bible is true because it claims to be the word of God, and God cannot lie. (It needs to be established as the word of God first before it is known to be divinely reliable.)
The Book of Mormon is true because it says that if you pray and ask God to show you the truth, and you ask with true intent, you will see the truth. (Presumes the truth of the BoM, and that if you don’t get the positive answer, you are wrong, not the Book. Related also to the No True Scotsman fallacy.)
The physical universe is all there is, therefore the supernatural does not exist. (The conclusion is just a restatement of the premise.)
Recognizing the fallacy: If in an argument the premises truth value depend on the truth of the conclusion, you have a circular argument.