The Death of Negative Corpus (Abridged Version)
Dennis W. Smith, BA, BSc
Presented at International Symposium on Fire Investigation, 2012
ABSTRACT
The Negative Corpus Methodology [NCM], the belief that the elimination of known potential fire causes (ignition sources), proves some unknown fire cause for which no evidence exists, has long standing in the fire investigation community. The 2011 edition of NFPA 921, Guide for Fire and Explosion Investigations finally repudiated and firmly rejected the NCM, although in some segments of the fire investigation community there is still deep-rooted use and reliance on this improper and unethical process.
This program is a follow-up to the 2006 presentation at ISFI International Symposium on Fire Investigation Science & Technology) “The Pitfalls, Perils and Reasoning Fallacies of Determining the Fire Cause in the Absence of Proof: The Negative Corpus Methodology.” That article made the case that the NCM relied on unsupported and faulty reasoning such as the appeal to ignorance and a disjunctive form of reasoning, often in the form of the disjunctive syllogism . Relying on these fallacies ultimately resulted in opinions that were neither valid nor reliable.
In addition to revisiting some of the fundamental logical reasoning fallacies relied upon using the NCM, this program will provide real-world examples of the application of the NCM; and, explore new studies that further demonstrate the procedural failings and shortcomings of the NCM to further expose it as an invalid and unreliable method for purposes of determining the cause of a fire. Lastly, the article will demonstrate how the NCM fails to meet the Daubert criteria concerning the reliability of expert opinion.