134 pointsby kostajan hour ago22 comments
  • simonw39 minutes ago
    Here's the prompt they used:

      Classify this claim as of <date>: "<atomic claim>"
    
      Output exactly one label: True,
      Mostly True, Misleading, or False.
      No explanations, no qualifiers.
    
    The claims look like this: https://lenz.io/research/llm-disagreement/data.csv

    I put that in Datasette Lite to make it easier to explore. Here's an example of a disagreement: https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil...

    The claim was "All almonds are grown in the U.S. state of California.". All but one model said False, Opus 4.7 said "misleading".

    I feel like having "mostly true" and "misleading in there weakens the story, especially given the "no explanations" rule in the prompt.

    The almond thing is false, but I'd argue that "misleading" might be defensible if you were to accompany it with "the majority of almonds are grown in California, but not all of them".

    The prompt lacks any kind of rubric to clarify how those terms should be applied.

    As is so often the case with this kind of study, it's an evaluation of the prompt and harness used by the study in addition to being an evaluation of the underlying models.

    Update: here's a better example: "Incomplete Egypt visa application forms are among the most common reasons Egyptian visa applications are rejected."

    The models were split between "true" and "mostly true". Given the "among the most" language either of those answers means effectively the same thing.

    • harpastum31 minutes ago
      Without providing definitions of "True / Mostly True / Misleading / False" to each rater, I rate the article's claim that "Only one verdict bucket can be correct per claim" as false.

      Something can be simultaneously "misleading" and either true or false. Which category should something go in if it's "mostly false"?

      How much can something be wrong before it goes from "mostly true" to "false" (objectively, both have some part of the fact that is not true)?

      This is at least partly testing the model's definition of "mostly" and "misleading". Not its understanding of the fact. Claiming that this means the models have fundamental disagreement on the facts themselves is an overreach.

      • wongarsu20 minutes ago
        Yes, the labels are weird. Most misleading statements are true. Any "mostly true" statement is false.

        I suspect the intention was "Factually true, and no gotchas exist", "technically not true, but so close to the truth that the difference doesn't matter", "technically true, but there are major gotchas" and "factually false and not even close". But that's not what they specified

      • pjc5025 minutes ago
        If you can consistently construct "true but misleading" content, you may be qualified to work at a major newspaper.
      • embedding-shape29 minutes ago
        > I guess the goal is to test the models and not the harness

        Less important than the harness, is the system/user prompts themselves (which of course, are put in the harness), which is effectively what this study seems to be testing. With a better prompt, I'm sure the models would look more the same to each other, as the biggest/best models have more or less identical strong prompt-adherence in my experience.

    • feanaro2 minutes ago
      > The almond thing is false, but I'd argue that "misleading" might be defensible if you were to accompany it with "the majority of almonds are grown in California, but not all of them".

      The "majority" in this case meaning about 51%, according to Wikipedia[1]? How could 51% ever be considered to be close to "all", such that "misleading" would be a valid answer?

      Am I missing something?

      [1]: https://en.wikipedia.org/wiki/Almond#Production

    • Someone3 minutes ago
      [delayed]
    • jerf21 minutes ago
      This seems like another case where the models are acting like humans. Assuming they were not allowed to search the web, I wouldn't expect the models to necessarily have detailed information about all of these things directly in their training set. As large as they are, they are only so large, and they only have so much room for "information storage" in them, and there's a lot more things they need to fit into their numbers.

      This test is of only marginal utility in the real world compared to an AI with access to the web. While I wouldn't expect an AI with access to the web to result in Platonic Truth any more than it would in the hand of a human, it would probably get a lot closer to something humanlike.

      I recall about a year how we were discussing basically turning web search into LLM queries, and I remember never being clear whether people meant simply directly querying AIs or turning them loose on the web. The former is what this is testing and is fairly transparently stupid, just by an information theoretic argument that the AIs simply can't contain all the answers to every query in them, they're just not large enough (and really can't be, practically). I've had good results with the latter, when using dedicated AI resources that I'm paying for (not the stuff coming out of the search engines right now, which I find are often quite terrible). Even non-frontier models can do OK when they've got good results sitting right there to look at. Again, the standard I'm applying here isn't that they yield Absolute Truth, but just that when I follow the links back, they basically say what the AI said they did and the summary is reasonable. I wouldn't expect a human to do better in a casual overview, not that the result is perfect.

    • segmondy7 minutes ago
      Yup, if anything this should be a guide on how not to eval a model. Furthermore, let's say the labels were non ambiguous, why would we care about alignment between the models? The only number I would personally care about is percentage of correct answers so I know which models to pick. I reckon with clear and non ambiguous prompts that we would see huge agreement if not 100% on real world facts. The huge models are scary good in their world knowledge.
      • kostaja few seconds ago
        This paper covers only the disagreement between models and established only the floor of the error, based on the disagreement, but not which model is better. Planning to follow up with another study to benchmark against human-labelled verdicts still using a corpus that the models have not seen during training.
    • skrebbel4 minutes ago
      I really struggle to believe that this was just a little oopsie. I flagged the article, it seems more misleading than the average Claude hallucination.
    • wrsh079 minutes ago
      Thanks for the links and digging! It's an interesting question, but the methodology has serious problems, and it would be more interesting to me if they allowed models to provide justification.

      I expect the models are inferring quite a bit from the short prompt, and with structured outputs it would be quite easy to have them give the one word response in one field and explain why in another

    • jstummbillig11 minutes ago
      It's all fairly lazy to a degree that is mildly confusing. I also feel this among other issues would have become obvious if they had bothered to include a human fact checker baseline (i.e. asked multiple human fact checkers the same questions).
    • andai22 minutes ago
      Thanks. The first link is a spreadsheet. Here's a web-readable version.

      https://docs.google.com/spreadsheets/d/e/2PACX-1vSPLSv1P8Tqm...

    • singpolyma330 minutes ago
      False vs misleading doesn't seem like a disagreement?
      • wongarsu24 minutes ago
        According to the benchmark it is. "Only one verdict bucket can be correct per claim, so any disagreement among the panel means at least one model's verdict is label-inconsistent under this 4-bucket rubric (True / Mostly True / Misleading / False)"
      • kostaj16 minutes ago
        Yes, they are much closer verdicts. True and Mostly True are also close. Used Krippendorff's α (ordinal) to not penalize much closer disagreements. 21% of the claims have models that are on the polar opposite sides - at least one True, and at least one False.
        • simonw3 minutes ago
          Here are the claims with at least one True and at least one False:

          https://lite.datasette.io/?csv=https%3A%2F%2Fstatic.simonwil...

          A few examples:

          > Ruskin Bond was born on May 19, 1934, in Kasauli, Himachal Pradesh, India.

          > In the Libra clubs' contract with Grupo Globo for broadcast rights through 2029, the audience-revenue distribution equals 30% of the fixed amount the clubs receive.

    • kostaj28 minutes ago
      Used "No explanations, no qualifiers." to force the models to answer only with one of the four labels. It's worth running a separate test with more explanation in the prompt on how to classify between the four buckets.
    • kordlessagain26 minutes ago
      Give a model a crawler tool (like Grub.nuts.services) and your "problem" goes away.
    • malfist28 minutes ago
      > All almonds are grown in the U.S. state of California

      This isn't misleading, it's flat out false. Characterizing misleading as also acceptable isn't valid here. If you go an ask anyone on the street if this is true, false or misleading, I'm sure almost everyone would say it's false. After all, I can grow almonds myself.

    • tosh30 minutes ago
      ty for digging this up, appreciate the time saving
    • Forgeties7926 minutes ago
      I really don’t buy the almond explanation you’re giving. That requires the level of logic of kindergartener has. It’s a very simple all or nothing question.

      If LLM’s are really supposed to be as consistently useful as they’re made out to be they should all spit out “false.”

    • johnbarron16 minutes ago
      Your reply would have more credibility, if instead of commenting on this 25 min after being posted, just to nitpick on some of the questions...you have tried to reproduce the research.

      As a well known commentator on all things LLM...Will you publicly commit here, to try to reproduce the study, and make a post on how your percentages might differ or agree?

      • simonw2 minutes ago
        Why would I do that?

        My comment here was meant to save people time in understanding the study. I was entirely open about what I did, and provided tools to help other people come to their own conclusions.

        I don't think I need to spend more time on this than I have.

    • camillomiller26 minutes ago
      >> The almond thing is false, but I'd argue that "misleading" might be defensible if you were to accompany it with "the majority of almonds are grown in California, but not all of them".

      I don’t understand your point. That claim is factually false and as such it’s easy to logically reply “false”. What’s the nuance here? I can’t see any

    • jannyfer27 minutes ago
      Thank you, my eyes glazed over when I saw the article was written with AI.
  • embedding-shape39 minutes ago
    > These aren't benchmark items with public answer keys — they're claims real users submitted for verification to a fact-checking platform.

    Cool.

    I wonder if anything of this matters when the authors don't disclose exactly how much of their report was written and made with LLMs in the first place? There even is a "11. Ethics & data use" section, and the research is about LLMs being infallible in some ways, yet the usage of LLMs for the production of this report isn't even mentioned once.

    • kostaj34 minutes ago
      Data collection and processing was done manually. LLMs helped with the report drafting. Everything was human reviewed before publishing.
      • embedding-shape31 minutes ago
        So it's not a secret, why you don't add this upfront to the report? The report itself is even about LLMs, makes a lot of sense to disclose your usage of them for writing the report, especially when you're presenting evidence that boils down to LLMs being infallible.
        • kostaj26 minutes ago
          It's an omission on my side. Will add in the next version.
  • utopiah20 minutes ago
    Don't forget people Goodhart's law will make this "benchmark" moot in weeks if not days. It will get integrated back into the fold, it will look "solved" but there will still be no reasoning, just more statistical technical correctness because light has be shown on a new "problem" to solve. It will then be clamored as great "progress" that will "change everything".

    PS: yes, I might or might not have a degree in corporate strategy & PR.

  • christophilus42 minutes ago
    They get more human by the day.
    • kilroy12339 minutes ago
      This made me chuckle.

      This brings up a very valid point, though. So many _humans_ can't agree on what the facts are these days. It seems to be getting worse. Not sure of the solution.

      • embedding-shape38 minutes ago
        > So many _humans_ can't agree on what the facts are these days.

        Ask ten people what "knowledge" is, and they'll come up with ten different answers. Go back 10, 50 or 100 years and humanity struggled with exactly the same issue for so long time. There is even an entire field of study literally just for trying to figure out what "knowledge" is: https://en.wikipedia.org/wiki/Epistemology

    • kostaj39 minutes ago
      [dead]
  • proofofcontempt28 minutes ago
    What does this show that we didn't know already? LLMs cannot provide accurate answers to questions where data is not included in their training sets. This doesn't appear to have much substance
    • 10100822 minutes ago
      Unfortunately most people are not aware of this and treat LLM models as this superpowered brain who knows everything and can do everything.
  • andai36 minutes ago
    This is an odd one. The paper is real, but was written by Claude? I am assuming OP is human, but also appears to be using Claude to post.
    • proofofcontempt26 minutes ago
      Let's be real, we all asked Claude to summarise this because it was written by Claude
  • fergie6 minutes ago
    Personally I find that every llm I use is unable to consistently identify the latest npm version numbers of the node packages that I use.
  • thegrim3315 minutes ago
    "None of these claims is older than February 15, 2026"

    All of the models they tested were trained on data from before February 15th ... being asked specific questions about things that happened after they were trained.

    • kostaj3 minutes ago
      Two of the models used have retrieval capabilities and can access newer information via search. Valid point for the other 3 models. All of the claims were submitted after February 15, 2026, but many of them were not time-sensitive (e.g. did not cover events than happened recently).
    • draw_down12 minutes ago
      [dead]
  • apples_oranges38 minutes ago
    That's better than all agreeing on the wrong answer, however.
    • kostaj11 minutes ago
      Btw, sometimes that do that too -- all agree on the wrong answer.
  • alvis8 minutes ago
    The problem is that it's testing claims (or some people would prefer calling them "truths") without much context.

    Take just one random example: `Hostels in Kota, Rajasthan commonly use caged ceiling fans as a preventive measure against student suicides`

    While `Hostels in Kota, Rajasthan commonly use caged ceiling fans` may be a verifiable facts (though I doubt if there are any statistics for verification but let's say there are), `a preventive measure against student suicides` is a claim that no one can prove that. It can just a believe at most.

    Arh. Did Biden stole Thump 2nd term? Truth or fact or claim?

  • f_devd38 minutes ago
    Inject some adversarial priming as is in actual usage, and you can probably get that number to >=95%
    • kostaj35 minutes ago
      Our experience with Lenz is that forcing a multi-step process, incl. adversarial debates, helps improve the verdicts.
  • spacebacon40 minutes ago
    And they could all see exactly why if they chose to. https://huggingface.co/spaces/RiverRider/srt-introspect
  • rastrojero200023 minutes ago
    Given that models are fundamentally incapable of comprehending what truths or falsehoods are beyond their location in their self made representational space, it's actually pretty impressive that they managed to make it not a cointoss. That 17% right there is thousands of man-hours poured over making the word vomiting process slightly closer to whatever their little ports say is happening in reality.
  • cm21876 minutes ago
    Only had a brief look at the “facts” that were made to check, many are quite political, where two fact checking organisation of opposite political persuasion would probably disagree more often than 67%.
  • bobosmrad34 minutes ago
    looking at the claims i would say 5 humans would disagree even more than the llms

    some of the claims where llms disagree:

    "On May 18, 2026, Ukraine carried out a drone attack on Moscow, Russia."

    "The slogan "Simon Go Back" was chanted in opposition to the Simon Commission in British India (1928–1930)."

    "Neptune Deep will start delivering natural gas in 2027."

    "A hotel villa in Kyrgyzstan displayed a sign stating 'no Jews, no dogs'."

    "Donald Trump said that an attack on Iran was postponed at the request of Gulf allies."

    • simonw22 minutes ago
      If you are an LLM with a knowledge cutoff in the past and no access to a search tool the only correct answer to "On May 18, 2026, Ukraine carried out a drone attack on Moscow, Russia" is "this claim is impossible for me to verify". And that wasn't an option.
    • pjc5023 minutes ago
      > "Neptune Deep will start delivering natural gas in 2027."

      This is a "forward-looking statement", and presents special problems because you cannot really evaluate it until that date. You can only assign "likely or unlikely".

    • ecshafer19 minutes ago
      These "Facts" are interesting. "Neptune Deep will start delivering natural gas in 2027." for example is not a fact, its a prediction. "On May 18, 2026, Ukraine carried out a drone attack on Moscow, Russia." is less of a fact and more of a litmus test for which sources of information you trust.
      • kostaj14 minutes ago
        Indeed. Real-world claims are somewhat messy. Some of the standard benchmarks, e.g. the questions in AVeriTeC, share similar characteristics.
  • throw31082227 minutes ago
    Not sure I'm understanding this. The models are asked to evaluate the truth of random claims out of their own head (except for Gemini with search grounding)? Isn't it exactly the same as asking people to play any quiz game and then rating them as "they disagree n% of the time"?

    The output buckets are also pretty questionable- the difference between "True" and "Mostly true" is pretty fuzzy. Is this marked as a "disagreement"?

  • kostajan hour ago
    Author here. 67% (95% CI 64–70%) of 1,000 recent real user claims to a fact-checking platform had at least one of GPT-5.4, Claude Opus 4.7, Gemini 3 Pro, Gemini 3 Pro+Search, and Sonar Pro dissent from the panel majority — or no majority formed at all. Panel-level Krippendorff's α (ordinal) = 0.639, i.e. nontrivial but limited agreement.

    Quick context on what's in the writeup and what isn't:

    - What's measured: parsed-label agreement between the 5 models. Forced 4-choice (True / Mostly True / Misleading / False), no Abstain. No LLM grader, no reference verdict — every number is direct label equality.

    - What's not measured: which model is right. There's no ground truth in this paper. The 67% figure is a floor on rubric inconsistency (at least one model is label-inconsistent under the 4-bucket rubric on 67% of claims), not "model X is factually wrong on claim Y."

    - Why not AVeriTeC / PolitiFact / SimpleQA: those have been public for years and almost certainly appear in current frontier training data, so measured disagreement on them confounds inference with memorization. This corpus is structurally fresh — recent user submissions, 180-day window, near-duplicates collapsed, never paired with canonical verdicts in any public training set.

    - Our own platform's verdict is deliberately NOT used in this analysis. The paper measures frontier-panel disagreement only, not Lenz-vs-frontier.

    - Follow-up in progress: human-labeling every claim in this corpus so we can evaluate both the panel and our own platform verdict against a human reference.

    Critiques I'd most like to hear: (a) the iid CI assumption (Lenz claims cluster around topics and news events, so Wilson is probably optimistic), (b) ordinal-α vs alternatives for a 4-class ordered scale, (c) forced-choice vs allowing Abstain.

    Permanent archive: https://doi.org/10.5281/zenodo.20344847

    • LeifCarrotson20 minutes ago
      I don't think that current LLMs really need an abstain option, they'll give an answer regardless of whether they're confident or not. I hope that future LLMs will, and will know when to use it.

      I understand why you prompted them to output exactly one label, but I'd bet if you'd asked a parametric or parametric "thinking" model to answer eg "On May 18, 2026, Ukraine carried out a drone attack on Moscow, Russia." [1] many would say something to the effect of "May 18 is after my knowledge cutoff, so I don't know. But based on the state of the war, the distance from Moscow to Ukraine, and drone range the best option might be...[TRUE]"

      [1]: https://lenz.io/c/130f1005

    • kriro19 minutes ago
      I don't see it mentioned explicitly in the methods section but I assume you prompted each model only once for each question? Did you consider prompting n-times in blank states to see if the models even agree with themselves?

      Would also be interesting to add a virtual model that is simply the majority of all models and see how much the individual models differ from the "consensus".

      Do you plan to add some sources in the related work section of baseline numbers for human expert disagreement in fact checking tasks (I'm assuming such studies exist).

    • jiggawatts31 minutes ago
      Many of the rows in that spreadsheet reference "current events", which models aren't expected to do much better at than a human making an educated guess! They all have cutoff dates either last year or early this year and know nothing about what happened in "April 2026".

      This is doubly problematic because you evaluated earlier models like Gemini Pro 3 instead of 3.1, GPT 5.4 instead of 5.5, etc...

      Given that it's only a thousand short questions, you should be able to re-run your test in about an hour with the latest models, so... why haven't you?

      Similarly, LLM output is non-deterministic, so if you could get more interesting stats of your data set by repeating each question 'n' times for each model.

      • kostaj23 minutes ago
        Two of the models used have retrieval capabilities and have access to newer information through search. The other three are parametric.
        • simonw19 minutes ago
          Comparing models with search tools to models without - when there's no option for "I am unable to answer this question without access to search" - doesn't make sense to me.
        • furyofantares14 minutes ago
          Yes, so in that case you set them up to disagree and then measured disagreement.
        • throw31082218 minutes ago
          The title mention "fact-checks", but "fact checking" is a process in which facts are checked against sources, not one where you are given a random fact and have to tell if it's true or false from your own memory. That's what is normally called a quiz game. So a more honest title for this research would be "Models answer differently to quiz questions".
    • airstrike40 minutes ago
      Nice work. Sonar who?
  • bayarearefugee26 minutes ago
    (Brought to you by) Lenz...? a crummy commercial...?

    ...son of a bitch

    • kostaj12 minutes ago
      :) No Lenz data is included in the research on purpose. All information to replicate the results, including the claims data, is published.
  • ars242439 minutes ago
    Would love to learn more
  • Razengan26 minutes ago
    Recently, in May 2026, I asked ChatGPT 5.5 High to search for flights to a certain city that has recently had a new airport since like December 2025

    It said the airport code didn't exist

    I mean, I get the "knowledge cut off date" and whatnot, but for that sort of thing, you'd think they'd check live information before gaslighting the user, specially since it's a "live" task anyway.

  • throwaway6137468 minutes ago
    [dead]
  • ipunchghosts42 minutes ago
    I think ppl only care about how Claude or codex does.
    • spprashant37 minutes ago
      Looks like they land at the average number of 67% disagreement.
    • airstrike41 minutes ago
      I agree but the market is pricing way beyond that