# Not only X but also Y Part of [The AI Tells Index](https://feedsquad.com/ai-tells). A tell signals low effort. It does not identify an author. Skilled writers produce every shape listed here, some of them daily, and automated detectors misread those writers for it at rates measured above 60 percent on non-native English prose. Nothing in this index proves that a machine wrote anything. Read an entry as one piece of evidence to weigh against the false-positive notes printed beside it. ## Facts - Id: additive-contrastive-negation - Category: Rhetorical and discourse (rhetorical) - Subcategory: contrastive-negation - Also known as: additive contrastive negation, correlative coordination, not just X but Y - Status: Active. Currently signals low-effort writing. - Severity: medium - Evidence grade: corroborated (named independently by multiple credible secondary sources) - Languages: en - Added: 2026-08-15 - Updated: 2026-08-17 - Page: https://feedsquad.com/ai-tells/additive-contrastive-negation ## Description Two coordinated members joined by a correlative pair. The first is negated, the second added on top. Silvennoinen separates this additive subtype of contrastive negation from the replacive subtype, which denies one description and substitutes another; that one has its own entry and its own rule. Grammar calls the frame correlative coordination, and it is ordinary taught English. The catalogued version is narrower: both members name the same thing at two levels of abstraction, so the sentence widens without adding a fact. The rule below skips the placeholder form, where the members are a bare X and a bare Y, because that is how the construction gets named rather than used. ## Why it reads as machine-written The frame produces the feeling of a scope claim at no cost. A writer who has measured two effects names both, and the reader can check either one. A writer who has one sentence and needs weight puts the small version first, negates it, and adds the large version after the correlative. Wikipedia files the family under negative parallelisms. Density decides. One in a page is prose. Four in a short post is a cadence looking for content. ## Detection Type: deterministic (a regular expression, run as written) Scope: sentence ECMAScript regular expression. The build validator compiles it and tests it against this entry's own specimens. ```regex \bnot\s+(?:only|just|merely|simply)\s+(?![XY]\b)[^.;!?\n]{1,80}?\s+but\b ``` Flags: gi ## Examples Constructed specimens. Written for this index. Never quoted from anyone's posts. ### Specimen 1 Before, exhibiting the tell: > Our scheduler is not only a calendar but also a strategist for your entire content operation. Planning ahead is what makes publishing consistent, and consistency is what makes any of the rest of it worth measuring at all. The right cadence looks different for everyone, which is why the tool adapts to the way you already work rather than the other way around. After, repaired: > The scheduler moved 40 posts for us in July when a launch slipped by a week, and it caught the two that would have gone out during a client embargo. Note: Figures in this repair are invented for the specimen. ### Specimen 2 Before, exhibiting the tell: > The report is not merely a summary but a call to action for every team involved. After, repaired: > The report ends with four asks. Each one names the team that owns it and the date it is due, and all four land before the March board meeting. ## False positives Who legitimately writes this way. Academic writers use the correlative frame to make a genuine scope claim, and it is standard taught English with a grammar of its own; Silvennoinen documents it as ordinary register variation rather than a defect. Grant applications and abstracts run on it because the genre rewards stating both a narrow and a broad contribution. Second-language writers taught English through formal writing courses reach for it more often than a monolingual would, since the correlative is explicitly drilled. A reviewer separates the two cases by testing the second member: if it names something the first did not, and something a reader could check, the sentence is doing work. ## Model attribution Not tied to a vendor. The Washington Post counted not-just-X-but-Y variants in roughly six percent of shared ChatGPT chats in July 2025, a figure our research pass recorded second hand and did not verify at source, so it is reported here as context and not as a rate. No peer-reviewed source assigns the construction to a model family. ## Platform notes - wikipedia: Catalogued under negative parallelisms with the shortcut WP:AIPARALLEL. The same section states that human writers use the form commonly. - linkedin: The frame is house style in professional-network copy and predates chat products there, so a single hit on that surface carries little weight. ## Sources 1. Wikipedia: Signs of AI writing https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing (tier: community; accessed 2026-08-14) 2. Silvennoinen, Contrastive negation in English, VARIENG 19 (2017) https://varieng.helsinki.fi/series/volumes/19/silvennoinen/ (tier: peer-reviewed; accessed 2026-08-14) ## Status history Ids are permanent. A retired tell keeps its id and its page. - 2026-08-15, Active: Opened as active. Wikipedia lists the negative-parallelism family as a current sign, and Silvennoinen gives the construction a precise grammar and separates it from the replacive form. The human base rate is high, which is why severity stays moderate and the entry says the signal lives in repetition. ## License CC BY 4.0. https://creativecommons.org/licenses/by/4.0/ Attribution: The AI Tells Index, feedsquad.com/ai-tells Reuse the data, including commercially. Keep the attribution line. --- Dataset version 1.0.0. Schema version 1. Part of [FeedSquad](https://feedsquad.com). Built by [Herman Foundry](https://hermanfoundry.com) from Levi, Finnish Lapland.