Seth M. answered • 03/14/19

Professor of Philosophy with Expertise in Classical and Symbolic Logic

Yes, circular reasoning is always a fallacy -- an error in reasoning -- because, strictly speaking, it isn't really reasoning but just a repetition of a claim.

In a sound argument, the conclusion is implied by (or inferred from) the relationship of properly structured premises, but should not be explicitly or simplistically present in any *single* premise. For example:

John is a man.

John is unmarried.

An unmarried man is a bachelor.

Therefore, John is a bachelor.

This is a trivial, simple argument. However, the conclusion is not explicitly present in any single premise. Rather, it is derived from the relationship among the premises.

If, instead, we had as the conclusion "John is male," this would seem to be circular, as it is simply a restatement and repetition of premise one. In addition, the conclusion "John is not a woman" is also arguably circular, as it can be trivially inferred from a single premise.

This is considered a fallacy because simply restating a claim, even if in a subtly-different way, isn't really "reasoning."

The other, important issue here is that we need to be able to test premises for truth. The test by which we can discern whether a conclusion is true is the soundness of the argument -- the structure, clarity of the truth upon which it is based. However, each premise is, in a sense, also the conclusion to some other implied argument. These other arguments, however, must be independent of the current one and, instead, grounded in different or prior reasoning. If a premise and the conclusion are effectively the same, then we cannot perform this inspection in a meaningful way, for it is appealing to itself for justification of its own truth (which is precisely what is meant by a circular argument, or "begging the question").

Seth M.

07/25/19

JOHN D.

Incorrect. Circular Reasoning is ALWAYS valid. Deductively, In all cases a Premise 'P'is true, The same premise is True. Now, your conclusion, 'P' rests on the Assumption that 'P' is true. In a debate the conflicting party does not share that assumption. In order to PROVE the Assumption 'P' in the context of a debate, you'll need to use assumptions that are shared with the people you're debating with. The criteria for soundness is that the argument is BOTH valid, and the premises are in fact true. Your premise in this case is 'P', and assuming it is true does not mean 'P' is true. You must first derive 'P' from facts already known to be true. Thus, there's nothing invalid about circular reasoning, but nothing can be said about the soundness of certain circular arguments because more information is needed to determine whether the premises are in fact true.07/25/19