Language first. Truth is a separate problem.
A base language model predicts language rather than retrieving verified truth. Connected tools can supply information, but retrieval alone does not establish that the final answer is supported.
Modern AI can write with extraordinary range and precision. It can also produce an answer that sounds finished when its facts, sources, assumptions, or reasoning are not ready to rely on.
A hallucination may be an invented fact, a fabricated source, a distorted summary, or an unsupported conclusion. The dangerous version is not absurd. It is plausible enough to pass ordinary review.
A base language model predicts language rather than retrieving verified truth. Connected tools can supply information, but retrieval alone does not establish that the final answer is supported.
Novel questions, unusual combinations of ideas, incomplete prompts, recent events, and long reasoning chains can push a model beyond the patterns it can use reliably.
Specific language, clean structure, and authoritative tone can make weak support feel strong. A citation may be real yet fail to support the claim placed beside it.
AI produces polished work at machine speed. Human review is slower, and the reviewer often asked because they did not already know the answer. That is an assurance problem, not a writing problem.
Search, retrieval, citations, larger context windows, model agreement, and human review can all improve an answer. Each remains useful. None, by itself, decides whether the finished response is admissible, repairs it under explicit constraints, and checks the repaired result again.
The missing layer is control between what AI may fluently say and what a person or system should rely on.
Coherence identifies, contains, and repairs unreliable AI output. Its proprietary Coherence Reliability Engine sits outside the generative model, preserves the original candidate, controls the repair path, and rechecks the result before release.
This is designed to reduce reliability risk, not make every answer universally true. Consequential work still deserves the right human and professional review.