The hypothesis makes a strong, falsifiable prediction: detectors flag register (formulaic, low-perplexity institutional prose) rather than actual AI authorship. The strongest direct support is a single-document diagnostic test: ZeroGPT scored the 1987 Constitution of the Philippinesβdrafted and ratified decades before LLMs existedβas 98.5% AI-generated. This is a near-decisive single case because ground truth (human authorship) is certain, isolating genre/register as the only plausible driver .
Two converging lines corroborate the mechanism. First, detector error varies systematically by textual population: across 30 detectors, English L2 student essays showed consistently higher false-positive rates than L1 essaysβanother register-adjacent signal independent of any AI exposure . Second, in a blinded medical-school grading study, expert human assessors identified AI vs. student sources at only 53% (36/68)βnear chanceβwith perceived "writing style" the most cited (unreliable) rationale, and one assessor using AI detection tools classified zero responses correctly. Human judgment, like detector judgment, appears keyed to surface style rather than provenance .
Note: the 98.5% value is a single-document anecdote from a narrative review (n=1 text, one detector); the 53% figure comes from a small exploratory study (10 assessors, 68 responses, one institution). Neither represents a systematic genre-vs-exposure benchmark.
What is missing: no supplied evidence systematically benchmarks constitutions, legal templates, and formulaic academic prose across multiple detectors. The Weber-Wulff paraphrase-evasion findings and near-chance human accuracy (40β55%) further suggest detectors rely on fragile stylometric cues that legal boilerplate happens to share with LLM output . Falsification would require a multi-detector, multi-genre corpus (pre-LLM vs post-LLM institutional texts) in which false positives track authorship rather than register.
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