Dilbert: And we know mass creates gravity because more dense planets have more gravity.
Dogbert: How do we know which planets are more dense?
Dilbert: They have more gravity.
Dogbert: That's circular reasoning.
Dilbert: I prefer to think of it as having no loose ends.

–Scott Adams, Dilbert (March 1, 1999)

Apparently there are universal rules of good thinking. They seem to apply to everyday living and to academic disciplines like science and others. We don’t get to choose them; they are imposed on us, but science doesn’t know for sure by whom or what. The rules seem to be very rigid such that if you break them other people might scold you and bad things can happen. One of these rules is called circular reasoning, also called begging the question. It says that your conclusion cannot be part of your premise. It’s just not allowed. Another rule is that if you make a claim about something you have to be able to back it up. You need evidence.