Source-Grounding Does Not Prevent Semantic Governance Failures Evidence Across Multiple RAG Architectures

Prior research showed architecture was the key to LLM hallucinations (Evans, Two Missing Primitives, 2025) with missing primitives semantic prioritization and semantic revocation playing a major role; (Evans, NotebookLM, 2025) and demonstrated that frontier language models exhibit systematic hallucinations when required to maintain strict semantic dominance, globally constrained interpretations that conflict with local context. These failures arise not from knowledge gaps but from architectural absence of governance primitives: the ability to prioritize one interpretation over competitors and revoke that authority when context changes. 

Models with access to all correct meanings still hallucinated 100% of the time under constraint, recovering instantly when interpretation switching was permitted.

This finding raises a critical question: Do Retrieval-Augmented Generation (RAG) architectures (which constrain outputs to verified sources) provide the missing semantic governance layer?

RAG vendors claim source-grounding prevents hallucinations. We tested this empirically across three independent implementations (Google NotebookLM, Anthropic Claude Projects, and Perplexity) using identical semantic governance diagnostics to earlier testing establishing the two missing primitives. 

Finding 1: Source access does not prevent governance failures. All three systems exhibited 100% hallucination rates under strict semantic dominance despite having correct source information. All three achieved 100% accuracy under revocable semantic dominance, proving they possessed correct meanings but lacked governance control.

Finding 2: Systems explicitly confirm semantic interpretation is not source-constrained. When queried directly, all three stated they use training data rather than retrieved sources for meaning resolution. Perplexity tested with RAG disabled versus enabled (20+ authoritative sources retrieved and cited) produced identical hallucination patterns in both conditions.

Finding 3: Citation does not equal semantic constraint. Perplexity cited sources defining “riverbank” while simultaneously stating “bank means financial institution” and generating implausible scenarios (hikers sitting on bank buildings, canoes pulled onto financial institutions).

Source-grounding constrains retrieval but does not introduce semantic governance primitives. RAG architectures fail to address the governance layer where these hallucinations occur. The vendor claims tested are empirically false. Enterprise deployment strategies predicated on source-grounding as a reliability solution require reassessment. Our research is grounded in documenting user experience with LLMs, so wherever possible we work with prompt windows, but we strongly encourage enterprise replication, falsification and other testing of these findings.