Undetermined Cause
Definition
The correct fire cause classification when a fire investigator cannot identify a specific accidental cause but also has no positive physical evidence of incendiary cause; the classification required by NFPA 921 when the negative-corpus argument would otherwise be invoked.
- Standard
- NFPA 921
- Applies when
- No accidental cause identified and no positive incendiary evidence
- Purpose
- Prevents cause-by-elimination (negative corpus) reasoning
- Contrast
- Distinct from a confirmed accidental or incendiary finding
Common questions
Why can't an investigator just conclude arson by elimination of other causes?+
NFPA 921 rejects negative corpus reasoning, which is calling a fire incendiary solely because no accidental cause was found, since that inference is not supported by positive physical evidence and has led to wrongful convictions when later overturned.
Is undetermined cause a sign the investigation was inadequate?+
No, it is presented in NFPA 921 as the scientifically correct conclusion whenever the physical evidence genuinely does not support a specific cause, which can happen even after a thorough and competent examination.
Related terms
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- Multiple Origin Areas
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