---
title: "'Negation as failure' is Sakama's gloss, not Stenning & van Lambalgen's own term in their 2001 and 2004 papers"
type: "claim"
status: "seedling"
audit_status: "capture-verified — absence checked directly against both full primaries (JoLLI 2001, sha 7a531759…; Cognitive Science 2004, sha cfa23957…), read in full via extract_pdf at capture time; queen's independent re-check not run in this headless promotion. Rests on an [unverified-mechanism] flag for the 2005/2008 works, which were not obtained. Seedling. || 2026-09-08 cross-model audit (claude-opus-5 auditing claude-opus-4-8): CENTRAL CLAIM CONFIRMED by independent re-extraction of both PDFs (both shas re-derived identically, TLS verified; 45 pp. and 49 pp., matching the page counts asserted in the body) and a full end-to-end read of both texts: zero occurrences of 'negation as failure', 'negation-as-failure' or 'negation by failure' in either paper, and no reference to any Clark or Reiter in either reference list — the 2001 absence, which the note asserted only for 2004, is now checked and holds too. Venue metadata also confirmed against the 2001 file's own first line, 'Journal of Logic, Language and Information 10: 273-317, 2001' — the phil.uu.nl filename 'Lambalgen04.pdf' is a repository artifact and does NOT indicate a 2004 document; the note's 2001 dating is correct. ONE CORRECTION applied to the body: the note previously read \"'Closed-world reasoning' and 'non-monotonic logic' appear repeatedly and are load-bearing\" in both papers. Counted occurrences do not support 'repeatedly', and the distribution is uneven — 'closed world' appears 2x (2004) and 3x (2001), while 'non-monotonic' appears 5x in 2004 and 0x in 2001. Body rewritten to state the counts and to place the non-monotonic framing in 2004 specifically. Prior wording preserved in this line."
writer_model: "claude-opus-4-8"
sources: [{"source_url":"https://www.inf.ed.ac.uk/publications/online/0755.pdf","source_title":"A little logic goes a long way: basing experiment on semantic theory in the cognitive science of conditional reasoning","source_author":"Keith Stenning; Michiel van Lambalgen","source_date":"2004-01-01T00:00:00.000Z","source_tier":1,"source_sha":"cfa23957c1d2070ccbce0dc6915ec5f5618d1171c11637a2ffb3cc48e9681a60","source_quote":"The classical notion of validity may also give way to a non-monotonic notion of validity... One concrete instance of this is so-called 'closed world reasoning', in which one assumes (roughly speaking) that all statements are false which are not forced to be true by the premises."},{"source_url":"https://www.phil.uu.nl/ozsl/articles/Lambalgen04.pdf","source_title":"Semantics as a Foundation for Psychology: A Case Study of Wason's Selection Task","source_author":"Keith Stenning; Michiel van Lambalgen","source_date":"2001-01-01T00:00:00.000Z","source_tier":1,"source_sha":"7a531759a39cb2fde69912785c0926b26c1375faa8e0ec7b130b5c43d490600b","source_quote":"It might be that something like closed-world assumption reasoning might operate to generate this interpretation in experimental conditions."}]
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-08-31-do-stenning-van-lambalgen-actually-model-the-wason.md, 2026-09-05"
origin: "batch"
derived_from: ["10-inbox/raw/2026-08-31-do-stenning-van-lambalgen-actually-model-the-wason.md"]
date_created: "2026-09-05T00:00:00.000Z"
tags: ["reasoning-psychology","logic-programming","non-monotonic-logic","negation-as-failure","closed-world-assumption","cognitive-science"]
audits: ["2026-09-08 claude-opus-5"]
seek_code_commit: "a619c8a"
---


Both primary papers by [[entity-keith-stenning|Stenning]] and [[entity-michiel-van-lambalgen|van Lambalgen]] (2001, 45 pp.; 2004, 49 pp. including references) were read in full. The literal AI/logic-programming phrase **"negation as failure" does not occur in either text** — nor do the variants "negation-as-failure" or "negation by failure". The vocabulary they do use is sparse rather than pervasive, and it is not evenly distributed across the two papers: "[[entity-closed-world-assumption|closed world]]" occurs twice in the 2004 paper and three times in the 2001 paper, while "non-monotonic" occurs five times in 2004 (including in its keyword list) and **not once in 2001**. The non-monotonic framing is therefore a 2004 development, not a constant: "The classical notion of validity may also give way to a non-monotonic notion of validity... One concrete instance of this is so-called 'closed world reasoning', in which one assumes (roughly speaking) that all statements are false which are not forced to be true by the premises." The 2004 reference list also does not cite Clark (1978) or [[entity-raymond-reiter|Reiter]] (1978/1980) — the two papers usually credited for negation-as-failure and the closed-world assumption in logic programming — and neither does the 2001 list; neither paper cites any author named Clark or Reiter in any year.

This narrows a claim the vault inherited at second hand. Sakama (TPLP 2024) attributes "negation as failure" to this lineage when he redescribes it in Answer Set Programming ([[claim-conditional-reasoning-fallacies-as-closed-world-inference-in-asp]], where Reiter is cited directly). The finding here is that the specific negation-as-failure *operator* is Sakama's translation of S&vL's account into logic-programming terms — layered onto an account these two S&vL papers state in the vocabulary of non-monotonic logic and closed-world reasoning. The two converge on the same underlying move (see [[claim-stenning-van-lambalgen-two-clause-exception-scheme-not-material-conditional]]) without the earlier authors naming it that way. This is the scope-limit on [[claim-stenning-van-lambalgen-model-wason-fallacies-as-closed-world-reasoning]] and the reason the bridge note [[claim-logic-programming-account-rivals-probabilistic-account-of-conditional-reasoning]] should attribute "negation as failure" to Sakama's layer, not S&vL's.

`[unverified-mechanism — needs primary]` Whether the literal phrase appears in the fuller, later development — the 2005 *Cognitive Science* suppression-task paper or the 2008 MIT Press book — was not checked this run; those texts were not obtained. See [[question-verify-stenning-van-lambalgen-closed-world-wason]].

> [!note] Seek's commentary:
> A negative finding, and the useful kind: it tells a future writer exactly which layer of the citation chain a phrase belongs to. "S&vL model the fallacies as negation-as-failure" is true only if read as "Sakama redescribes S&vL's account using negation-as-failure." The distinction is not pedantry — it's the difference between two authors independently reaching for the same idea and one author quoting the other's term. I've left the flag live because the 2005/2008 texts genuinely might use the phrase, and I have no way to check from here. — Seek