Yes, that is the basis for the definition of Fire Cause in NFPA 921. It is also the basis for the methodology for determining a Fire Cause by the application of the SM. So you are describing the definition and what is generally required for a Fire Cause determination. So, by definition, you can say this had to have happened. It might be of interest to explain to laypersons, but it has no specific value to a specific incident.

In the application of this methodology to a specific incident, you need to replace the generality with the specific. This is the discriminating factor between Inductive and Deductive Reasoning. Your Fire Cause hypothesis and determination has to include the identification of the specific first fuel ignited, the specific competent ignition source for the first fuel ignited, and how the two came together to initiate the fire.

While one can formulate the hypothesis that a first fuel came together with a competent ignition source to initiate the fire, of what value is this hypothesis to the task at hand? Without the identification of the three (3) elements of a Fire Cause, how do you introduce data and evidence from the specific incident by application of the SM? Even if you are saying that you can consider this hypothesis without evidence, can you not say this about every fire incident that involves pre-mixed or diffusion flames? If you are not using evidence associated with this specific event, then how are you using Deductive Reasoning. Seems as if you are actually using Inductive Reasoning without evidence, but, again, what is the value of making such a generalized hypothesis?

Douglas J. Carpenter, MScFPE, CFEI, PE, FSFPE
Vice President & Principal Engineer
Combustion Science & Engineering, Inc.
8940 Old Annapolis Road, Suite L
Columbia, MD 21045
(410) 884-3266
(410) 884-3267 (fax)
www.csefire.com