As tests of truth, both consistency and coherence are relativistic criteria. Instead of measuring a belief directly against an outside reality, they measure a belief against other beliefs. If that belief is consistent with or coheres with already-held beliefs, then it is considered true. If it fails to be consistent or to cohere, then it is discarded as false.
Read Article: Truth as Consistency & Coherence
Consistency and coherence are good for evaluating established truth or a verifiable hypothesis. On the other hand, lack of consistency and coherence is often a good sign of something new – some new truth to be pursued.