This is a subcategory of the Fallacies of Presumptions and it’s also known as “Circular Reasoning” or Tautology –This is when the conclusion of an argument is incorporated into one of its premises (or when the truth of a premise depends upon the conclusion).

Example 1: “*How do I know evolution is true? Because it is a fact!*“. This argument is asserting (A) that evolution is true on the basis of “(B) that it is a fact. But (A) is merely a restatement of (B). A person arguing this way has merely assumed what he is trying to prove and merely assuming something is no proof at all.

Example 2: “*Miracles are impossible because they cannot happen*“. The conclusion is merely a restatement of the premise.

Example 3: “*Young-earth creationists are wrong because radiometric dating shows that rocks are billions of years old*“. The problem with this argument is that young-earth creationists do not accept the assumptions that have gone into radiometric dating (see book “Thousands Not Billions” and “*Radioisotope and the age of the earth vol II*“). So by accepting that radiometric dating is reliable, the arguer has already assumed that young-earth creationists are wrong, and has THEN concluded that young-earth creationists are wrong. This begs the question.

It would seem that “begging the question” is not legitimate because it is arbitrary. We cannot merely assume as a premise what we are trying to prove. So when someone begs the question, we might response: “*You have simply assumed what you are trying to prove. This is arbitrary. Do you have a reason for your conclusion, or have you simply arbitrarily asserted it?*”