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

Limits of evidence without argument

againstThis argument, if it holds, weighs against the claim.constitution →Evidence assembled in a safety argument retains value even if the argument's reasoning is flawed

The argument

Because statistical testing alone cannot demonstrate the ultra-low failure rates required of safety-critical systems, the empirical evidence in a safety case supports only modest risk bounds by itself; the argument is what extrapolates from that evidence to the claimed assurance level, so when the argument fails, most of the case's claimed assurance goes with it and the evidence retains only a small fraction of the original value.

Does it work?

Not yet evaluated.

Premises

UnassessedNo current assessment. Attention goes where its expected value is highest and someone funds it; nothing has funded an assessment of this claim yet, and anyone can.constitution →Statistical testing alone cannot demonstrate the ultra-low failure rates required of safety-critical systems

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 25, 2026
The premise that testing alone cannot demonstrate ultra-low failure rates is among the best-established results in the dependability literature, and the inference from it is valid: most of a safety case's claimed assurance resides in the argument, so a flawed argument forfeits most of it. But the conclusion bounds the retained value rather than eliminating it, so the argument contradicts only a strong reading of the claim, not the modest reading on which it was assessed.