Is circular reasoning always a fallacy?

Question

Suppose the following dialogue: >... >"I accept only one notion of land property. Namely, 'I am doing my stuff here, therefore I am here". >"But this means," he responded, "you can break into any place and stay there, using this rule." >"There is another rule, though. Right to act in its most natural sense, 'I am here, therefore I am doing my stuff here." >"But do not these rules put together become circular reasoning?" >"Of course, they do," I put my head closer to him, "and this is exactly that rare case when circular reasoning is not only sufficient, but is necessary." >"But why is that? Circular reasoning never was a correct argument." >"There are many circular things happening in nature. Life forms, for example, exist only in order to produce new life forms or to prolongate their own lifetime. Is there any reason to say this can't be the case for reason itself? Why must reasoning not be circular?" >... Can circular reasoning ever be justified? For example, we know all the words in our languages can't be defined using other words without the use of circularity. We know logic can't prove itself without circularity. Are these arguments rational? Are there any other arguments where circular reasoning is still rational?

Answer 1

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").