Circular reasoning is a common logical fallacy. It is a form of the Fallacy of Presumption. In these fallacies, an argument sounds coherent and compelling, but is actually dependent on one or more faulty or unproven arguments . In circular reasoning, each claim loops around and rests on the assumption of one of the other claims. Thus, no single starting point is ever conclusively and independently established.
“Donald Trump says that he is trustworthy. But Donald Trump is a liar. You can’t trust liars. When Donald Trump says that he is trustworthy, he is lying.”
“Crooked Hillary is crooked because she’s untrustworthy. She can’t be trustworthy because she’s crooked.”