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Abstract
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We are happy to see a Commentary [1] about our article "(Mis)use of Scientific Measurements in Forensic Science" [2]. However, the Commentary suffers from three major errors that undermine the criticisms it levels.
First, the Commentary criticizes our "apparent insistence that every call be regarded as either "correct" or an "error"." This reflects a confusion about the status of the decision (correct or incorrect; true or false) with the actual decision itself. The actual decision -whether it is identification, exclusion, or inconclusive- can have the status of being either correct or incorrect. For example, the status of an identification decision is correct when called in reference to a same-source comparison that has sufficient detail to justify an identification, otherwise the identification decision is incorrect. The same logic applies to exclusion decisions, and inconclusive decisions when an appropriate experimental design is utilized (see [2]).
Second, the Commentary rejects our proposal to include a critical category of inconclusive evidence in error rate studies, and states that "We must deal with the fact that ground truth always has two categories." From a metaphysical perspective, the authors are correct: two items either do -or do not- originate from the same source. But the relevant question is whether sufficient quality or quantity of information exists in the evidence to make a source determination. For example, consider a cartridge casing that was discharged on a freeway, run over by dozens of vehicles, and then swept into a sewer for months to further degrade; that casing may not contain any information pertinent to making a source determination, therefore it is inconclusive evidence. In such cases, an inconclusive decision would be the only correct decision, despite the fact that the casing in question either did -or did not- originate from the same source as the comparison casing. Put differently, the relevant question is not the ontological or metaphysical perspective of what exists, but the epistemological perspective of what we can know, what we can justifiably conclude given the information available, i.e., whether there is sufficient quality and quantity of information that justifies making a source determination [3]. Otherwise, the evidence is inconclusive...
Language: en |