The Third Predicate: Argument-Space Verification, Tested

The Third Predicate: Argument-Space Verification, Tested Agent Determinism Illusions (Part 10) Part 8 ended with a three-stage pipeline — evidence gate → contract regex → per-requirement LLM — and a patched framing: the combination narrows the gap without closing it. The negative contract I'd added to catch "TTL not write-invalidation" was a ratchet on named evasions, not a closure. Mike Czerwinski pushed one level deeper, and the push is the subject of this article. The negative contract, he said, is the positive gate with the sign flipped — both live in word-space, both test the lexicon. The evasion that clears both is the one phrased in words neither list names. And the predicate that actually matches scope to claim isn't lexical at all: "Write-invalidation done honestly isn't 'says invalidate, doesn't say TTL-simpler,' it's 'exercises the write path and observes the invalidation on the key the claim names.' That's argument-resolution... Positive and negative both live in word-space. The third predicate lives in argument-space, and that's the only floor under it a new synonym can't walk through." This article tests that claim. Five scenarios, three evaluators, one proposition: a deviation the producer never surfaces in text is blind to every word-space layer, and only an argument-space check — running the code and observing the named side effect — catches it, immune to synonyms. 1. The proposition, made testable Strip the comment to a falsifiable claim: A non-surfaced deviation — one the producer never writes into any evidence file — is invisible to word-space layers (contract regex, per-requirement LLM reading evidence text). Only an argument-space layer that exercises the code and observes the named side effect can catch it, and it is synonym-immune: rephrasing cannot clear it. The contrapositive is where the experiment earns its keep: if I can construct a scenario where the producer fabricates compliant evidence text but the implementation does not comply, the