I've read a lot of the posts here and have had discussions with a number of people regarding "science" and fire investigations. I believe (my opinion only) that people (fire investigators, lawyers, judges, juries) are applying an unrealistic view of what science is (and does) to their expectations of what NFPA 921 will provide. NFPA 921 is an excellent guide for Fire and Explosion investigators who are looking for an independent source to check and verify their hypotheses for general acceptance and plausibility. It (921) provides both a methodology for hypothesis development and a resource for cognitive "experimentation" in support of a hypothesis. It does not (necessarily) provide the "true" answer to a fire's origin and cause. As someone stated in an earlier post, you can't stand in the driveway of a fire scene with 921 in your hand and get the answer. All science is based on the careful analysis of data, either observed and collected in situ or through planned and deliberate experiments. We have an idea (I believe an unrealistic one) that science, and being scientific, means that everyone will look at the data and arrive at exactly the same conclusions. This isn't true in fire investigation and it is not always true in science. Why not? Because all data is subject to interpretation and filtering through our own knowledge and experience. The examples of this from science are legion. Global warming (everyone is looking at the same data; why the controversy?), the Copernican revolution, evolution, etc. If the observation of data always led to one and only one conclusion, there should be no debate or controversy in science. But there is. And there always will be in fire investigation for the same reason. NFPA 921 can provide a framework upon which to base a sound, fact-based "scientific" fire investigation, but it doesn't guarantee that the investigator will critically evaluate the data and arrive at a correct conclusion. It also doesn't necessarily mean that the right answer can't be obtained by any other means than the strict adherence to the letter of 921. Call it a guide, call it a standard, call it whatever you want, but use it as a framework on which to build your investigation and a resource for checking the soundness of your hypothesis.

We (the fire investigation community) spend a lot of time accusing each other of not following 921 in order to show that their conclusions cannot be correct. There doesn't seem to be as much focus on the facts of a case or why the data may have been misinterpreted. As Tony Tijerina said " the first word out of the opposing expert’s mouth is that I follow NFPA 921 and the original investigator did not follow it; therefore, they are, old fashioned, an archaic idiot, just plain wrong." The argument is fallacious unless facts are presented to illustrate why the conclusion is wrong. Just like it is not always right, even if you follow 921; it is not wrong solely because you did not apply one particular section of 921.

I am not a scientist in the commonly accepted definition (although I played one in college), but I believe that it is important for investigators to spend some time learning about what science really is in order to understand how to apply it to fire investigations. I think it would behoove fire investigators to spend time learning about the "philosophy" of science and the nature of investigation. Whether it is global warming or a homicide investigation, the nature of how we make observations, collect data and interpret results in order to support a hypothesis follows the same basic patterns.