Scores by kind of claim
Each kind of claim is scored on its own, out of 100: the share that held up, with the range it likely falls in. Fewer resolved claims give a wider range.
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Factual claims
Statements about the present or the past, checked against the record: did they hold up?
80 74 86 -
Predictions
Statements about events outside the person's control, checked once they fell due: did they come true?
Insufficient record: 4 predictions resolved, 5 needed for a score.
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Promises
Commitments to the person's or organisation's own future action, with something to deliver: was it delivered?
85 74 94 -
Guidance
A company's own figures for its results over a period, checked against what it then reported.
Insufficient record: 0 guidance claims resolved, 5 needed for a score.
All types combined: 81 (likely 76 to 86, high confidence), from 86 claims: 70 factual claims, 16 promises. It mixes kinds of claim in different proportions for different people, so compare people kind by kind.
Mark Zuckerberg's claims
40 claims
“I think what you’re starting to see are some of the labs are building, training more advanced models, and then not even releasing them”
Mark Zuckerberg, Meta CEO, interviewed on Sources podcast 15 September 2026 Transcript: Mark Zuckerberg Interview on Meta's Muse AI Agent (Sources Podcast) (The Singju Post)
Zuckerberg said he thinks some AI labs are starting to build and train more advanced models and then not release them.
Mostly true True in substance, wrong in a detail.
What would count as true or false
Judge the claim's substance, as of 2026-09-15: some AI labs were starting to build and train more advanced models and then not release them (publicly or generally). It is hedged ('I think', 'starting to'), so a few clear cases are enough. True: credible evidence (lab announcements, system cards, or reliable reporting) shows at least one, and preferably several, AI labs had trained models more capable than their public releases and chose to withhold them or limit access to a small set of partners, instead of releasing them generally. Mostly true: the evidence shows withheld or restricted-access advanced models, but mainly from a single lab, or access was limited instead of fully withheld. Mixed: the cases mostly look like normal pre-release delays, not decisions to withhold, with only ambiguous examples of models being held back. Mostly false: the only evidence is speculation or normal staged rollouts, with no credible case of a lab deliberately not releasing a more advanced model. False: credible evidence shows labs were releasing their most advanced models promptly, with no withholding.
Evidence
- Claude Fable 5 and Claude Mythos 5 Anthropic · 9 June 2026
“Claude Mythos 5 is restricted to Glasswing partners (with cyber safeguards lifted) and soon to select biology researchers (with biology and chemistry safeguards lifted) only, until our broader trusted access program is available.”
- Claude Fable 5 and Claude Mythos 5 Anthropic · 9 June 2026
“In April we began Project Glasswing, releasing the first Mythos-class model (Claude Mythos Preview) to only a limited group of cyber defenders and critical software infrastructure providers.”
- OpenAI to limit access to Astra model's advanced cyber features due to hacking concerns Fortune · 1 September 2026
“But only a handful of partners will get access to its most advanced cybersecurity capabilities as OpenAI works to balance helping companies prevent cyberattacks while not empowering attackers at the same time”
- Amodei says Anthropic's safety delay may have cost it an AI lead The New Stack · 21 October 2026
“Anthropic first released Claude Mythos Preview in April through Project Glasswing, giving selected partners, including Amazon, Apple, Microsoft, CrowdStrike, and the Linux Foundation, access to the model’s vulnerability-discovery capabilities for defensive work while keeping it out of reach of ordinary developers.”
Reasoning
Anthropic's June 2026 announcement says its Claude Mythos 5 model was restricted to Glasswing partners, and soon to select biology researchers, until a broader trusted access program is available [E1]. It also says Claude Mythos Preview went in April only to a limited group of cyber defenders (E1, E2). The New Stack independently reports that this model was kept out of reach of ordinary developers (E4). Fortune reports that OpenAI would give only a handful of partners access to its Astra model's most advanced cybersecurity capabilities (E3). That is a second, less clear-cut case, because it restricts certain capabilities rather than withholding a whole model [E3]. The evidence shows advanced models with restricted access, but the clearest cases come mainly from one lab, and access was limited to partners rather than fully withheld. That matches the criteria for mostly true.
Cite this claim
Mark Zuckerberg, “Zuckerberg said he thinks some AI labs are starting to build and train more advanced models and then not release them.” (said 15 September 2026). Verdict: mostly true. Reliability API, claim c_7efa686cc75e, method 0.1.0+3f84d14d. https://epistacklabs.com/claims/c_7efa686cc75e
Claims without a verdict
- Unresolvable 144
- Not yet due 17
- Own records only 41
- Not researched 223
- Not checkable 1,060
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