Negative-Corpus Argument
Definition
An invalid standalone conclusion in fire investigation that a fire was incendiary because no accidental cause was identified; rejected by NFPA 921 (2021 edition), the ENFSI Best Practice Manual, and the UK Forensic Science Regulator as insufficient without positive physical evidence of incendiary cause.
- Status
- Rejected as invalid standalone reasoning
- Rejected by
- NFPA 921 (2021 edition)
- Also rejected by
- ENFSI, UK Forensic Science Regulator
- Field
- Fire investigation
- Requires instead
- Positive physical evidence of incendiary cause
Common questions
Why is a negative-corpus argument considered unreliable?+
Because ruling out every accidental cause does not itself prove an incendiary one. It is reasoning from absence of evidence, and testable causes can be missed, destroyed, or simply not investigated.
How should investigators establish an incendiary cause instead?+
Through positive physical indicators, such as multiple unconnected points of origin, laboratory-confirmed accelerant residue, or recovered ignition device components, that directly support an incendiary origin.
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