To use an analogy, imagine that a prison warden gets paid by the number of prisoners kept. We are in the early days of forensic science and there is a poorly understood crime. In fact, in a recent survey, less than 30% of detectives could recognize the crime from a case study. For the warden, this general ignorance is not a danger; it is an opportunity to “educate” those charged with apprehending criminals. He hires experts which use the credibility of forensics in a demonstration, not to expose gross errors when relying on circumstantial evidence, but only to prove that many of the real criminals are “getting off scot-free,” knowing full well that detectives in the field don’t have the requisite infrastructure and that they can and will only avail themselves of their inherited, poorly understood reliance on circumstantial evidence. (So ironically, the reason why so many criminals go free is because of the prevailing cultural reliance on circumstantial evidence.)
It was the expert’s duty to correct the misunderstanding, and so to protect himself, he adds in a verbal disclaimer, with euphemisms like, “limitations to circumstantial evidence,” and using the word “caution” with the worst example of failed evidence imaginable, which was nonetheless used in his presentation as proof that large numbers of criminals are running free. (See Lancaster, PA here). Culture is a fait accompli, and so the mild disclaimers have no effect on the prevailing use of circumstantial evidence. That brief disclosure aside, he returns to the call for action, “dangerous criminals are getting away with it” and then tells the detectives that “circumstantial evidence is standard practice and recommended.” The prevailing cultural bias does all the downstream work for the Warden. In short, the warden engineers a social condition the outcome of which swaps out the difficult-to-find real targets and swaps in the easy-to-find innocent.