trailIndependent review of safety cases, as institutionally practiced, often fails to detect major deficiencies
Defeater analysis and independent adversarial review can substantially mitigate confirmation bias in safety cases
Independent adversarial review detects significant flaws that safety case developers overlook
The Nimrod precedent· for
The Nimrod Review found the Nimrod safety case was a paperwork exercise that missed key dangers
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QinetiQ failed to properly carry out its role as independent advisor on the Nimrod safety case
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Structural incentives toward sign-off· for
Safety case reviewers are commonly commissioned by the developer, creating incentives toward confirmatory sign-off
Safety case assessors are typically contracted and paid by the developer or project whose system they review
Evaluators paid by the party they evaluate face incentives to reach favorable conclusions
Accreditation, liability, and reputational stakes give commissioned safety assessors countervailing incentives toward rigor
Regulatory review does catch shortfalls· against
Nuclear regulators regularly identify serious shortfalls in reactor safety cases requiring resolution
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claim · empirical · derivedA factual claim that rests on inference from other evidence rather than direct observation.constitution →claim page ↗︎
Independent review of safety cases, as institutionally practiced, often fails to detect major deficiencies
↑SupportedEvidence favors the claim, but the chain is incomplete or the sources are secondary.constitution →credence 0.70Credence, 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 →
2depended 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.