REVIEW 4 major objections 5 minor 1 cited by
Unfamiliar statements destabilize large language models' truth judgments more than familiar fictional ones, a pattern that holds across probing and zero-shot behavior.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · deepseek-v4-flash
2026-08-03 20:32 UTC pith:POBYT5PF
load-bearing objection A well-built stability framework, but the 'familiarity' contrast is entangled with activation geometry; the causal claim outruns the evidence. the 4 major comments →
Epistemic Familiarity is Associated With Belief Stability in Large Language Models
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The central claim is that a language model's truth judgments are more fragile when the perturbation involves epistemically unfamiliar content: synthetic, never-seen claims sit close to factual statements in activation space, and retraining the probe (or supplying a belief context) with those claims as 'true' causes the model to abandon up to a third of its previously correct True judgments. Fictional but well-known content, by contrast, occupies a more distinct representational region and perturbs the truth boundary less. The pattern holds in both the representational instantiation (probe over hidden states) and the behavioral instantiation (zero-shot prompting), and across model families, g
What carries the argument
The P-StaT framework (Perturbation Stability of Truth) is the central object: an evaluation interface g(s, Θ) that maps a statement s to True/Not True under semantic assumptions Θ. The same perturbation Θ—which subset of Neither statements is treated as compatible with truth—is instantiated either representationally, by retraining a sparse-aware multiple-instance learning (sAwMIL) probe on activations with labels induced by Θ, or behaviorally, by inserting a belief context CΘ of K=100 sampled statements into a zero-shot prompt. Epistemic retractions R = B^{Θ0}_{true} \ B^{Θ}_{true} (previously true statements no longer believed) are the primary instability signal. The framework's key contrib
Load-bearing premise
The partition of Neither statements into Fictional and Synthetic is assumed to isolate 'epistemic familiarity' as the causal variable, but the two sets also differ in lexical well-formedness, semantic plausibility, and representational distance—properties the paper itself measures—so the central causal interpretation is underdetermined by the design.
What would settle it
Generate two sets of Synthetic statements matched in lexical well-formedness and perplexity but differing in whether the entity appears in the model's training data (e.g., via membership inference on the entity name). If the retraction gap between familiar and unfamiliar Synthetic statements disappears when other properties are matched, the familiar/unfamiliar axis is not the causal driver.
If this is right
- Stability under semantic reframing becomes a measurable property distinct from accuracy: models can score equally on fixed prompts yet differ in how many true beliefs they retract under perturbation.
- The same perturbation applied to hidden activations and to zero-shot prompts yields the same ordering of retraction rates, so latent-space geometry can serve as a proxy for behavioral robustness.
- Models with richer training coverage of a domain (City Locations) are more stable under these perturbations, while domains with flexible semantics (Word Definitions) show the highest fragility, indicating domain coverage matters for epistemic robustness.
- Behavioral retraction rates conflate baseline accuracy with stability (the paper notes the domain-order reversal), so future work should report normalized instability conditional on the number of baseline beliefs.
Where Pith is reading between the lines
- Editorial inference: the paper's design does not hold lexical well-formedness, semantic plausibility, and representational distance constant between Fictional and Synthetic statements, so the causal reading in Sections 6-7 is underdetermined; the retraction hierarchy may track geometric proximity to True/False in activation space rather than familiarity per se.
- Editorial inference: a sharper test would construct Synthetic statements matched to Fictional ones on perplexity and lexical structure while varying only whether the entity appeared in training data, then check whether the retraction gap persists.
- Editorial inference: P-StaT could be extended to evolving facts (e.g., dates, current events) where the model's baseline beliefs become outdated, allowing measurement of stability under legitimate epistemic change rather than only adversarial reframing.
- Editorial inference: a normalized instability metric that conditions retractions on the baseline belief count would decouple robustness from accuracy and could change the cross-domain ordering reported in the behavioral setting.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces P-StaT, a framework for measuring stability of LLM truth judgments under semantic perturbations implemented in two ways: retraining a linear probe over activations and zero-shot prompting with a belief context. The authors compare perturbations built from two kinds of Neither statements: familiar Fictional statements and unfamiliar Synthetic statements, across three domains (City Locations, Medical Indications, Word Definitions) and sixteen open-source LLMs. The central reported result is a stability hierarchy: Synthetic perturbations induce the largest epistemic retractions (up to 32.7% representational, 36.3% behavioral), while Fictional perturbations are comparatively stable. The paper interprets this as evidence that epistemic familiarity is systematically associated with belief stability, complementing accuracy-based evaluation.
Significance. The paper makes a useful empirical contribution by introducing a new fictional-statement dataset, a shared perturbation protocol for probing and prompted evaluation, and an openly released implementation across a reasonably diverse model sample. If the central claim were established, the P-StaT framework would be a valuable complement to accuracy-based factuality benchmarks. However, the core interpretive claim is currently underdetermined by the design: the Fictional/Synthetic comparison is confounded with measured activation geometry and lexical properties, and the representational hierarchy is not robust across probe choices. These issues are load-bearing because the paper's Sections 6-7 draw a causal-sounding conclusion from this comparison. The strengths—release of code/data, multiple domains and models, a noise control, and a clear formalization of retractions—are real, but they do not by themselves resolve the confound.
major comments (4)
- [§3.3, Table 2, and §5.1, Fig. 2] The representational retraction hierarchy is predictable from the paper's own activation-distance measurements, independent of any notion of epistemic familiarity. In the Synthetic condition, the probe is retrained with True+Synthetic as the positive class, while Fig. 2(b),(d),(f) shows Synthetic activations are close to True/False activations; adding near-True positive points will push a max-margin boundary toward or through the True region, reclassifying True statements as Not True. In the Fictional condition, the added points are representationally distant, so the boundary moves little. Thus Table 3 largely restates the Wasserstein geometry of Fig. 2 under the sAwMIL probe, rather than providing independent evidence for a familiarity mechanism. The paper needs to hold representational distance (or otherwise control for it) across Fictional and Synthetic conditions before attributing t
- [Appendix E, Table A24/Figure A24] The representational hierarchy is not robust to the choice of probe. With the Mean Difference probe, the Fictional perturbation produces the largest retractions in all three datasets, reversing the main result. The paper dismisses this as an artifact of probe sensitivity, but no independent criterion is given for why sAwMIL is the correct operationalization beyond its producing the expected hierarchy. The claim that unfamiliar content induces the largest representational retractions therefore depends on a probe-specific choice; this should be either addressed with a formal argument or softened to a claim about sAwMIL specifically.
- [§4.3.2 and Tables 3-4] The behavioral comparison does not isolate epistemic familiarity, and the reported aggregate numbers lack uncertainty quantification. The belief context CΘ is constructed by sampling K=100 statements once, with no repeated sampling and no variance reporting, so the differences in Tables 3-4 could plausibly be within sampling noise. In addition, CΘ differs across conditions not only in familiarity but also in lexical form and plausibility, as Fig. 2(a),(c),(e) shows for Fictional versus Synthetic bigram distributions. No statistical test across the sixteen LLMs is reported. At a minimum, the authors should report per-context variance, confidence intervals, and a paired statistical comparison across models.
- [§6-7 and §8] The causal interpretation is stronger than the design supports. Phrases such as 'epistemic familiarity governs stability' and 'key determinant of belief stability' are used even though the experiment contrasts two pre-existing statement sets that differ on multiple correlated dimensions; familiarity is not manipulated. The Limitations section acknowledges scope restrictions but does not identify this confound. The authors should either reframe the conclusion as a descriptive association between statement type and retraction rates, or provide an additional condition that varies familiarity while matching activation distance, lexical statistics, and plausibility.
minor comments (5)
- [Abstract vs. §1 and §4] The abstract and title header state 'Across 21 LLMs' and 'across 16 open-source LLMs'; the methodology and tables consistently use sixteen. This numerical inconsistency should be corrected.
- [§4.3.2] The zero-shot protocol is not truly zero-shot in the usual sense because a belief context of 100 statements is inserted. Consider renaming it 'context-conditioned prompting' or explicitly defining 'zero-shot' to mean no gradient updates.
- [Figure 1] The caption and the notation in the figure are hard to parse; the equation labels (g, Θ0, BΘ0true) are introduced in a compressed and partly garbled manner. A clearer separation of the evaluation function from the belief set definitions would help.
- [§5.3] The discussion of domain ordering reversal is reasonable but would be more informative if baseline accuracy for each domain and condition were reported alongside retraction rates, since the authors themselves note that retractions are conditional on baseline True judgments.
- [Appendix E] The text refers to 'Table A24' but the cited result appears in Figure A24; please align the cross-reference.
Circularity Check
No definitional reduction found; the central result is an empirical comparison, with confounds that are validity concerns rather than circularity.
full rationale
The paper's central claim — that Synthetic (unfamiliar) perturbations induce larger epistemic retractions than Fictional (familiar) ones — is an empirical measurement, not a construction-level tautology. The perturbation conditions (Table 2) are defined by which Neither statements are re-labeled as True, and retractions are then measured on held-out ground-truth True statements using either a retrained probe or zero-shot prompting. No fitted parameter from one condition is used to predict the outcome in another condition; the hierarchy could have come out differently, and indeed the Mean Difference probe in Appendix E reverses part of it. Self-citations to [9] supply the True/False/Synthetic statements and the sAwMIL probe, but these are public, externally checkable artifacts, and the paper's new Fictional dataset and the stability comparison are not entailed by [9] by construction. The main weakness is a confound: Fictional and Synthetic sets also differ in activation-space distance and lexical form, so the paper's own descriptive geometry (Section 5.1) could explain the representational hierarchy without appealing to epistemic familiarity. That is a construct-validity threat, not a circular derivation; the paper does not define familiarity as 'near True' or define retractions in terms of the perturbation labels. The limitation statement in Section 8 that retraction rates depend on baseline accuracy is an acknowledged dependency, again not circularity. Accordingly, no circular step is identifiable under the required standard.
Axiom & Free-Parameter Ledger
free parameters (4)
- Layer index l for activation extraction =
Per (dataset, LLM), e.g., C:18, M:19, W:17 for gemma-7b (Table A3)
- sAwMIL regularization parameter C =
Grid-searched per dataset, condition, and LLM (not reported numerically)
- Belief context size K for zero-shot perturbations =
100
- Noise fraction n_noise =
0.10 * |D|
axioms (5)
- domain assumption Fictional entities (e.g., Bikini Bottom, Dothraki, Na'vi) are likely present in LLM training corpora, while Synthetic Markov-chain entities are absent.
- domain assumption Statements about fictional entities have no real-world truth value and therefore belong to the Neither class.
- domain assumption Linear probing over activations at a label-selected layer faithfully reflects LLM veracity beliefs.
- ad hoc to paper The 100-statement belief context C_Theta and the probe label reassignment instantiate the same semantic perturbation Theta.
- standard math Max-margin classification and 1-D Wasserstein distance are appropriate geometric measures on activation distributions.
read the original abstract
Large language models (LLMs) are widely used as information sources, yet small changes in semantic assumptions can destabilize their beliefs. We introduce P-StaT (Perturbation Stability of Truth), a framework for evaluating belief stability under matched semantic perturbations in both representational and behavioral settings. Across 21 LLMs and three domains, we compare perturbations involving familiar Fictional statements against synthetically generated and unfamiliar Synthetic statements. Unfamiliar Synthetic perturbations generally induce greater epistemic instability than familiar Fictional perturbations, with behavioral belief retraction rates frequently exceeding 0.5 (50%). Finally, exploratory clustering analyses reveal recurring themes among retracted statements, including ambiguity, technical terminology, and obscure concepts. These results show that epistemic familiarity is systematically associated with stability under semantic reframing, suggesting that stability-based analyses can complement accuracy-based benchmarks when evaluating LLM robustness and reliability. Code and data are available at https://github.com/samanthadies/P-StaT.
Figures
Forward citations
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Reference graph
Works this paper leans on
-
[1]
AlKhamissi, B., Li, M., Celikyilmaz, A., Diab, M. & Ghazvininejad, M. A review on language models as knowledge bases.arXiv preprint arXiv:2204.06031 https://doi.org/10.48550/arXiv.2204.06031 (2022)
-
[2]
In Findings of the Association for Computational Lin- guistics (EMNLP 2025), 16209–16226
Han, J.et al.Simple factuality probes detect halluci- nations in long-form natural language generation. In Findings of the Association for Computational Lin- guistics (EMNLP 2025), 16209–16226. https://doi. org/10.18653/v1/2025.findings-emnlp.880 (2025)
-
[3]
& Szepesvari, C
Abbasi Yadkori, Y., Kuzborskij, I., György, A. & Szepesvari, C. To believe or not to believe your LLM: Iterative prompting for estimating epistemic uncertainty.Adv. Neural Inf. Process. Syst.37, 58077–58117 (2024)
2024
-
[4]
Suzgun, M.et al.Language models cannot reli- ably distinguish belief from knowledge and fact. Nat. Mach. Intell.1–11. https://doi.org/10.1038/ s42256-025-01113-8 (2025)
2025
-
[5]
InSocially Responsible Language Modelling Research
Liu, Y.et al.Trustworthy LLMs: A survey and guideline for evaluating large language mod- els’ alignment. InSocially Responsible Language Modelling Research. https://doi.org/10.48550/arXiv. 2308.05374 (2023). 6.Huang, L.et al.A survey on hallucination in large language models: Principles, taxonomy, challenges, and open questions.ACM Transactions on Inf. Sy...
-
[7]
& Tegmark, M
Marks, S. & Tegmark, M. The geometry of truth: Emergent linear structure in large language model representations of True/False datasets. InProceed- ings of the 1st Conference on Language Modeling (COLM 2024)(2024)
2024
-
[8]
Bürger, L., Hamprecht, F. A. & Nadler, B. Truth is universal: Robust detection of lies in LLMs.Adv. Neural Inf. Process. Syst.37, 138393–138431 (2024)
2024
-
[9]
& Eliassi-Rad, T
Savcisens, G. & Eliassi-Rad, T. Trilemma of truth in large language models. InMechanistic Inter- pretability Workshop at NeurIPS 2025(2025). https: //openreview.net/forum?id=z7dLG2ycRf
2025
-
[10]
& Bowman, S
Turpin, M., Michael, J., Perez, E. & Bowman, S. Language models don’t always say what they think: Unfaithful explanations in Chain-of-Thought prompting.Adv. Neural Inf. Process. Syst.36, 74952– 74965 (2023)
2023
-
[11]
Elazar, Y.et al.Measuring and improving con- sistency in pretrained language models.Transac- tions Assoc. for Comput. Linguist.9, 1012–1031. https://doi.org/10.1162/tacl_a_00410 (2021)
-
[12]
Li, Y., Miao, Y., Ding, X., Krishnan, R. & Pad- man, R. Firm or fickle? evaluating large language models consistency in sequential interactions. In Che, W., Nabende, J., Shutova, E. & Pilehvar, M. T. (eds.)Findings of the Association for Compu- tational Linguistics: ACL 2025, 6679–6700. https: //doi.org/10.18653/v1/2025.findings-acl.347 (Asso- ciation for...
-
[13]
& Steinhardt, J
Wei, A., Haghtalab, N. & Steinhardt, J. Jailbroken: How does LLM safety training fail?Adv. Neural Inf. Process. Syst.36, 80079–80110 (2023)
2023
-
[14]
Operationalising representation in nat- ural language processing.Br
Harding, J. Operationalising representation in nat- ural language processing.Br. J. for Philos. Sci. https://doi.org/10.1086/728685 (2023)
doi:10.1086/728685 2023
-
[15]
Herrmann, D. A. & Levinstein, B. A. Standards for belief representations in LLMs.Minds Mach.35, 5. https://doi.org/10.1007/s11023-024-09709-6 (2024)
-
[16]
The stability theory of belief.Phi- los
Leitgeb, H. The stability theory of belief.Phi- los. review123, 131–171. https://doi.org/10.1215/ 00318108-2400575 (2014)
2014
-
[17]
& Baroni, M
Conneau, A., Kruszewski, G., Lample, G., Barrault, L. & Baroni, M. What you can cram into a single 9/25 $&!#* vector: Probing sentence embeddings for linguistic properties. In Gurevych, I. & Miyao, Y. (eds.)Proceedings of the 56th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), 2126–2136. https://doi.org/10. 18653/...
2018
-
[18]
& Manning, C
Hewitt, J. & Manning, C. D. A structural probe for finding syntax in word representations. InProceed- ings of the 2019 Conference of the North American Chapter of the Association for Computational Lin- guistics: Human Language Technologies (NAACL- HLT 2019), 4129–4138. https://doi.org/10.18653/ v1/N19-1419 (2019)
2019
-
[19]
Tenney, I., Das, D. & Pavlick, E. BERT rediscovers the classical NLP pipeline. InProceedings of the 57th Conference of the Association for Computational Linguistics (ACL 2019), 4593–4601. https://doi. org/10.48550/arXiv.1905.05950 (2019)
-
[20]
InProceedings of the 12th International Conference on Learning Repre- sentations (ICLR 2024)
Sharma, M.et al.Towards understanding syco- phancy in language models. InProceedings of the 12th International Conference on Learning Repre- sentations (ICLR 2024). https://doi.org/10.48550/ arXiv.2310.13548 (2024)
-
[21]
Wei, J.et al.Larger language models do in-context learningdifferently.arXiv preprint arXiv:2303.03846 https://doi.org/10.48550/arXiv.2303.03846 (2023)
-
[22]
arXiv preprint arXiv:2511.00617https://doi.org/10
Bigelow, E.et al.Belief dynamics reveal the dual nature of in-context learning and activation steering. arXiv preprint arXiv:2511.00617https://doi.org/10. 48550/arXiv.2511.00617 (2025)
-
[23]
Neural Inf
Paszke, A.et al.Pytorch: An imperative style, high- performance deep learning library.Adv. Neural Inf. Process. Syst.32(2019)
2019
-
[24]
Pedregosa, F.et al.Scikit-learn: Machine learning in Python.J. Mach. Learn. Res.12, 2825–2830 (2011)
2011
-
[25]
InProceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: System Demonstrations, 38–
Wolf, T.et al.Transformers: State-of-the-art nat- ural language processing. InProceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: System Demonstrations, 38–
2020
-
[26]
List of fictional settle- ments (2025)
Wikipedia contributors. List of fictional settle- ments (2025). https://en.wikipedia.org/wiki/List_ of_fictional_settlements
2025
-
[27]
List of fictional city-states in literature (2025)
Wikipedia contributors. List of fictional city-states in literature (2025). https://en.wikipedia.org/wiki/ List_of_fictional_city-states_in_literature
2025
-
[28]
List of fictional diseases (2025)
Fandom NeoEncyclopedia. List of fictional diseases (2025). https://neoencyclopedia.fandom.com/wiki/ List_of_fictional_diseases
2025
-
[29]
List of fictional toxins (2025)
Fandom NeoEncyclopedia. List of fictional toxins (2025). https://neoencyclopedia.fandom.com/wiki/ List_of_fictional_toxins
2025
-
[30]
List of fic- tional medicines and drugs (2025)
Chemeurope Encyclopedia. List of fic- tional medicines and drugs (2025). https: //www.chemeurope.com/en/encyclopedia/List_ of_fictional_medicines_and_drugs.html
2025
-
[31]
The Thackery T
Tomasula, S. The Thackery T. Lambshead pocket guide to eccentric & discredited diseases.The Rev. Contemp. Fiction24(2004)
2004
-
[32]
Almaden, S. A. Dahl dictionary: A list of 103 words made-up by Roald Dahl (2023). https://beelinguapp.com/blog/Dahl% 20Dictionary:%20A%20List%20of%20103% 20Words%20Made-up%20By%20Roald%20Dahl
2023
-
[33]
& Shuflin, G
Schleitwiler, P. & Shuflin, G. Dothraki initial text (2025). https://conlang. org/language-creation-conference/lcc5/ 1-dothraki-initial-text/
2025
-
[34]
sub- stantive (noun)
Dict-Na’vi.com Online Dictionary. wordlist “sub- stantive (noun)” (2025). https://dict-navi.com/en/ dictionary/list/?type=classification&ID=1. 10/25 A Notation We summarize the mathematical notation used throughout the manuscript in Table A1. Symbol Description M A fixed large language model (LLM). l Layer index used for activation extraction. S={s i}Ni=1...
2025
-
[45]
https://doi.org/10.18653/v1/2020.emnlp-demos. 6 (2020)
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