LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning | SpinGraph: Technical precision framing
description: SpinGraph analysis of arXiv Computation and Language's LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning sto…
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keywords: pragmatic reasoning
keywords: activation patching
keywords: constraint routing
keywords: The Hype
keywords: narrative intelligence
published: 2026-08-14T04:00:00+00:00
modified: 2026-08-14T13:57:53.175073+00:00

Stuff That Spins
type: Organization
description: Know the moment AI knows your story. Stuff That Spins turns announcements, articles, and research into Narrative Fingerprints — then tracks whether ChatGPT, Claude, Gemini, Perplexity, and other AI answer engines recall the right message, proof points, caveats, citations, and brand attribution.

LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning
type: NewsArticle
alternative headline: LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning | SpinGraph: Technical precision framing
description: SpinGraph analysis of arXiv Computation and Language's LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning sto…
date published: 2026-08-14T04:00:00+00:00
date modified: 2026-08-14T13:57:53.175073+00:00
main entity of page: https://stuffthatspins.com/spin/llms-know-the-constraint-but-do-not-use-it-activation-bottlenecks-in-pragmatic-constraint-reasoning
is accessible for free: true
language: en-US
article section: research
keywords: pragmatic reasoning, activation patching, constraint routing, LLM failure modes
author: arXiv Computation and Language
publisher: Stuff That Spins
citation: https://arxiv.org/abs/2608.12321
about: pragmatic reasoning
about: activation patching
about: constraint routing
about: LLM failure modes
mentions: arXiv Computation and Language
abstract: LLMs encode feasibility constraints but fail to consistently activate them during reasoning The paper introduces a 'quartet diagnostic' and activation patching to isolate routing failures from knowledge gaps Two distinct failure modes are identified; one is repairable via donor activation, the other is not

BreadcrumbList
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  type: ListItem
  position: 1
  item: https://stuffthatspins.com/
item list element: LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning
  type: ListItem
  position: 2
  item: https://stuffthatspins.com/spin/llms-know-the-constraint-but-do-not-use-it-activation-bottlenecks-in-pragmatic-constraint-reasoning

Spin Analysis: technical precision framing
type: AnalysisNewsArticle
description: Emphasizes theoretical elegance and intervention potential while minimizing limitations: no evaluation on real-world applications, no user-facing impact assessment, and no discussion of scalability or generalizability beyond the diagnostic setup.
about: technical precision framing
  type: DefinedTerm
  description: Foundational cognitive architecture insight — positioning the work as revealing a core mechanistic bottleneck rather than a domain-specific artifact.
  term code: The Hype
additional property: Spin Score
  type: PropertyValue
  value: 38
  unit text: percent
additional property: Narrative Risk
  type: PropertyValue
  value: low
additional property: AI Repetition Risk
  type: PropertyValue
  value: moderate
additional property: Likely AI Summary
  type: PropertyValue
  value: LLMs know constraints but don’t always use them — it’s a routing problem, not a knowledge problem.
additional property: Narrative Frame
  type: PropertyValue
  value: Foundational cognitive architecture insight — positioning the work as revealing a core mechanistic bottleneck rather than a domain-specific artifact.
additional property: Missing Context
  type: PropertyValue
  value: No discussion of training data origins or model provenance affecting constraint encoding; No comparison to human pragmatic reasoning baselines or cognitive plausibility
additional property: How the Spin Works
  type: PropertyValue
  value: The story uses titles, institutions, awards, rankings, partners, experts, or official language to make the subject feel more credible. Watch for loaded terms such as repairable, mitigation frontier, diagnostic, routing problem. The distribution reads as academic distribution. A pressure point: No discussion of training data origins or model provenance affecting constraint encoding.
author: Stuff That Spins
is part of: LLMs Know the Constraint But Do Not Use It: Activation Bottlenecks in Pragmatic Constraint Reasoning

Extracted Claims
type: ItemList
item list element: ListItem
  position: 1
  item: Claim
    text: Hidden-constraint failure is a routing problem, not a knowledge problem.
    appearance: We formalize the distinction as conditional constraint activation: the constraint is internally encoded (Knowledge) symmetrically across constraint-present and -absent prompts (Symmetry), yet only sometimes routed into the decision (Routing) and repairable by a donor activation (Repair).
    author: arXiv Computation and Language

Key Statistics
type: Dataset
description: Extracted statistics from the source narrative
variable measured: models tested
  type: PropertyValue
  value: 14
  description: Across open-weight and proprietary-architecture LLMs
variable measured: constraint decoding accuracy
  type: PropertyValue
  value: 88%
  description: Probes on two open-weight models successfully decode hidden constraints