Circular reasoning

Circular reasoning is an argument that assumes, explicitly or implicitly, the conclusion it is meant to prove. Its support therefore depends on the claim it is supposed to establish.

Begging the question: An informal fallacy in which an argument presupposes the truth of its conclusion. This is the standard logical label for circular support disguised as an argument.
Infinite regress: A sequence of explanations or justifications that continues without reaching a foundation. Circular support returns to an earlier claim; regress keeps demanding another justification.
Circular definition: A definition that uses the term being defined, or a close equivalent, without clarifying its meaning. Definitions can repeat a term's meaning instead of independently explaining it.
Argument: A set of claims in which premises are offered to support a conclusion. Circular reasoning is a defect in how an argument's premises support its conclusion.
Aristotle: An ancient Greek philosopher whose works shaped logic, metaphysics, ethics, and natural philosophy. Aristotle analyzed question-begging among the fallacies of argument in the Sophistical Refutations.
Premise: A statement offered as support for a conclusion in an argument. Circularity arises when a premise depends on the conclusion it is meant to support.
Tautology: A statement that is true by virtue of its logical form or the meanings of its terms. A tautology may be uninformative without functioning as an argument that assumes its conclusion.
Circular proof: A purported proof that relies, directly or indirectly, on the proposition it aims to establish. In mathematics, hidden dependence on the target proposition invalidates a claimed proof.
Deductive reasoning: Reasoning in which a conclusion is intended to follow necessarily from its premises. A deductive argument can be valid while still begging the question.
Sophistical Refutations: Aristotle's treatise examining deceptive arguments and methods for detecting them. It gives an early systematic account of begging the question and related fallacies.

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