The Legion of Reason podcast strives to promote the values of skepticism, secularism, atheism, and humanism. Recently it has come to my attention that one of our co-hosts, HJ Hornbeck, has been publicly advancing an argument based on what we feel is a fallacious application of the Bayesian inferential method to alleged sexual assault cases1. The purpose of this disclaimer is to explain why I and my co-hosts unanimously and adamantly reject this argument.
HJ argues that because claims of sexual assault that turn out to be false are relatively infrequent (<10% of reported cases) this should considered as evidence for the truth of any single particular claim of sexual assault, and further, that this should be included as evidence in a court of law.
Illustrative of the error in reasoning evident within this argument is one of the central premises upon which it rests, which can be stated as follows:
P1. X percentage of men commit sexual assault.
P2. M is a man.
C. Therefore the likelihood that M committed sexual assault is X percent.
The ecological fallacy is an error in reasoning defined as “the interpretation of statistical data where inferences about the nature of individuals are deduced from inference for the group to which those individuals belong.”2 This is particularly true if one treats the statistics as if they were gathered under controlled conditions, as is the case here (especially in the fallacious syllogism above). This is nothing more than taking a side based on statistics alone, and not on evidence directly related to the claim. That’s not skepticism.
In not accepting the claim as true on the basis of statistics alone as Haysn suggests, we are not therefor accepting the opposite claim (no assault took place). This would be a false dichotomy and we categorically reject such criticism. To call a claimant a liar or deluded is just as prejudiced as assuming the claim is true on the basis of no more than social statistics.
This argument is prejudicial, poisoning the well even before we get to the examination any evidence directly related to the particular claim in question. Comparing the statistical likelihood used in DNA evidence collected from a victim of sexual assault is not the same thing as using social statistics on sexual assault claims. One pertains to the claim at hand, the other does not. The farthest one can take the statistics on sexual assault claims is that because false claims are uncommon we should take every claim seriously, and we do believe any and all such claims should be taken very seriously. But to go further than this and use these same statistics as evidence to form an opinion on the truth of the specific claim is an abuse of science.
Even more egregious is the claim that no one is ever harmed by a false claim of sexual assault. I’ll put this in all-caps so we are not misunderstood: NO ONE FALSELY ACCUSED OF SEXUAL ASSAULT IS NOT HARMED BY THE FRAUDULENT CLAIM. The false nature of the claim is in itself harm, and aside from the possibility of false imprisonment, the standing of the accused in their career, family and community can be hugely affected, even after the false nature of the claim is discovered.
Each of us would be the first to admit that it is difficult to establish cases of sexual assault. But to tilt the playing field in such a manner is unconscionable. It is this very difficulty in validating such claims that the number of false claims remains low. There is little doubt that would change under the circumstances where the defendant must actually prove their innocence before even getting to a courtroom. It completely destroys the presumption of innocence, a concept of paramount importance in our legal system, and one of the foundations of our democracy. In short, the argument is not only anti-skeptical, it also undermines the core beliefs of humanism and secularism.
1http://freethoughtblogs.com/butterfliesandwheels/2014/09/guest-post-a-statistical-analysis-of-a-sexual-assault-case/ (http://freethoughtblogs NULL.com/butterfliesandwheels/2014/09/guest-post-a-statistical-analysis-of-a-sexual-assault-case/)
2http://en.wikipedia.org/wiki/Ecological_fallacy (http://en NULL.wikipedia NULL.org/wiki/Ecological_fallacy)