argumentA line of reasoning from premises to a conclusion. Like a claim, it belongs to no one who makes it.constitution →

The argument-error bound

forThis argument, if it holds, bears in favour of the claim.constitution →The probability of error in a safety argument bounds the confidence it can provide about low-probability risks

The argument

By the law of total probability, the overall probability of a catastrophe is at least the probability that the safety argument is flawed multiplied by the probability of catastrophe given a flawed argument. Because a flawed safety argument provides little evidence about the risk it assesses, the estimate reverts toward the prior whenever the argument fails, so the argument's error probability caps the assurance its conclusion can deliver; and since complex risk analyses historically exhibit error rates exceeding their claimed risk bounds, this cap binds in practice for the very small probabilities safety cases seek to establish.

Does it work?

Does it follow?: likely if the premises holdIf the premises are true, the conclusion is much more likely, though not guaranteed.constitution →
Do the premises hold?: 1 doubtful1 supported

Granting its premises, the bound follows nearly by construction from the law of total probability. It falls short of certain only because how much the estimate falls back toward the prior after a flaw depends on how severe flaws tend to be. The argument stands or falls mainly with whether a flawed argument provides little evidence, which is currently unsettled in general but strongest at extreme targets. Whether the bound matters in practice is carried by the historical error rates of complex analyses, which is supported.

Premises

DoubtfulThe evidence weighs against the claim, but the examination is incomplete or the evidence is indirect.constitution →A flawed safety argument provides little evidence about the risk it assesses
SupportedThe evidence favors the claim, but the examination is incomplete or the evidence is indirect.constitution →Complex risk analyses historically exhibit error rates exceeding their claimed risk bounds

Where it is made

Passages where sources make, criticize or mention this argument. They record where it appears, not how strong it is, and none has precedence over another.

No source is recorded as making it.

Earlier ratings

Jul 19, 2026
The total-probability step is valid, so the argument stands or falls with its premises. The historical premise, linked claim, is now supported and carries the practical force of the bound. The argument's real weight rests on linked claim, which is contested in its general form; the inference goes through only in the scope this claim occupies, extreme low-probability targets, where even an approximately correct flawed argument cannot secure conclusions far below the historical rate of severe analytical flaws.