Who Defines the Boundary of Explanation? A Governance Philosophy of the Two-Layer Architecture in Human-AI Interaction

The AI industry is gradually weakening its white-box safety mechanisms. As models exhibit increasingly stable performance, engineers are asking a logically self-consistent question: if the model is right 99.9% of the time, why retain a rigid rule-based system to override it? This paper does not contest the engineering logic of this trend. It converges on a narrower but more lethal question: who defines the threshold? When the industry says “AI is good enough and no longer needs to be explained,” who has the authority to make this judgment on behalf of the public? The paper distinguishes the necessity of post-hoc explanation (which can decline) from the possibility of process traceability (which must not be abandoned), and proposes a two-layer architecture: an output layer optimized for fluency, and a process-traceability layer that exists not to be used, but to exist. Its existence itself constitutes a constraint on power. Through the historical archetype of “Wang Mang”—trust completely established and then betrayed at the critical moment—the paper argues that any trust that can be built carries with it the possibility of being abused. The terminal proposition of explainability is not “how to make AI explainable,” but “who has the authority to decide when AI no longer needs to be explained.”