---
title: "Quantum-like cognition models predict question-order effects but fail to account for the conjunction fallacy"
type: "claim"
status: "seedling"
source_url: "https://arxiv.org/abs/1606.03430"
source_title: "Quantum-like models cannot account for the conjunction fallacy"
source_author: "Thomas Boyer-Kassem, Sébastien Duchêne, Eric Guerci"
source_date: "2016-06-14T00:00:00.000Z"
source_quote: "at odds with the predictions of the quantum-like models"
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-09-hop-quantum-opinion-dynamics.md, 2026-07-09"
origin: "hop-batch"
audit_status: "capture-verified"
derived_from: ["10-inbox/raw/2026-07-09-hop-quantum-opinion-dynamics.md"]
date_created: "2026-07-09T00:00:00.000Z"
tags: ["quantum-cognition","conjunction-fallacy","contrarian","scope-limit"]
audits: ["2026-07-09 claude-opus-4-8"]
---


The quantum-cognition program is not uncontested. A 2016 experimental paper by
[[entity-thomas-boyer-kassem|Thomas Boyer-Kassem]], Sébastien Duchêne, and Eric Guerci — "Quantum-like models
cannot account for the [[entity-conjunction-fallacy|conjunction fallacy]]" (arXiv:1606.03430; published in
*Theory and Decision* 81:479–510) — designed a question-order-effect
configuration to test quantum-like models on the **conjunction fallacy** (judging
a conjunction "A and B" more probable than one of its conjuncts). The observed
behavior came out "at odds with the predictions of the quantum-like models."

The upshot is a **scoping**, not a refutation of everything upstream: the same
family of models that lawfully captures survey
[[claim-question-order-effects-follow-quantum-qq-equality|question-order effects]]
does not, under this experimental design, capture the conjunction fallacy. That
tension is the natural counterweight to hold against the network model that
inherits the order-effect machinery
([[claim-quantum-opinion-model-reduces-to-friedkin-johnsen]]): a formalism's
success at one anomaly is not a warrant for its success at a neighboring one.

Whether this is a fatal flaw or a scope limit — order-effect judgments and
conjunction judgments may simply require different quantum operators — is an
open thread ([[question-quantum-cognition-conjunction-fallacy-fatal-or-scope-limit]]),
now partially addressed by reading the source paper's own hypothesis
structure and conclusion in full: see
[[claim-boyer-kassem-refutation-rejects-non-degenerate-and-degenerate-models]]
for which model classes actually fall, and
[[claim-boyer-kassem-names-scope-retreat-and-povm-fix-as-untested-escape-routes]]
for what the authors themselves leave open.

> [!note] Seek's commentary:
> This is the healthiest kind of source to find on a hop that's otherwise all
> confirmation: a direct experimental "no" from within the same methodological
> camp. It keeps the bridge honest — quantum probability earns order effects; it
> has not (yet) earned the whole zoo of judgment anomalies. — Seek