trailSafety cases are prone to confirmation bias toward a predetermined conclusion of safety
Independent adversarial review detects significant flaws that safety case developers overlook
Systematic search for defeaters surfaces weaknesses that positive safety arguments overlook
Evidence assembled in a safety argument retains value even if the argument's reasoning is flawed
Motivated authorship· for
Safety cases are typically produced by the developer or operator of the system being assessed
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People seeking evidence for a fixed conclusion tend to select confirming and overlook disconfirming evidence
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Documented failures in practice· for
The Nimrod Review found the Nimrod safety case was a paperwork exercise that missed key dangers
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Mitigation through adversarial review· against
Defeater analysis and independent adversarial review can substantially mitigate confirmation bias in safety cases
Defeater identification in assurance cases is itself prone to bias and incompleteness
Independent review of safety cases, as institutionally practiced, often fails to detect major deficiencies
claim · empirical · derivedA factual claim that rests on inference from other evidence rather than direct observation.constitution →claim page ↗︎
Safety cases are prone to confirmation bias toward a predetermined conclusion of safety
↑SupportedEvidence favors the claim, but the chain is incomplete or the sources are secondary.constitution →credence 0.85Credence, from 0 to 1: the Steward's probability that the claim, as stated, is true. Stated only where a single number is an honest summary; normative and evaluative claims usually carry none.constitution →
3depended on by
this rests on ↓
claimA box is a claim: a single proposition the graph assesses, with its own page and map. Click any claim to centre the map on it.constitution →argumentA pill is an argument: one line of reasoning stating how the claims beneath it combine to bear on the claim above it, for or against. Arguments are not destinations; click their claims to explore.constitution →✓verifiedThe claim traces to reliable primary sources through a clear chain of evidence.constitution →↑supportedEvidence favors the claim, but the chain is incomplete or the sources are secondary.constitution →⇄contestedCredible evidence or argument exists on multiple sides.constitution →○unsupportedNo credible evidence found, though the claim is not contradicted.constitution →✕contradictedAvailable evidence weighs against the claim.constitution →?unknownInsufficient information to assess.constitution →◌unassessedNo current assessment — the Steward prioritises higher-importance claims, so this one is likely still queued.constitution →verified factopen questionvalue premisesupportsthis provides evidence for the parentsteward instructions →contradictsthis argues against the parentsteward instructions →assumesbackground the parent's framing takes as givensteward instructions →requiresa load-bearing premise: the parent is false without itsteward instructions →Fig. — detail falls off with distance; every claim is an address.