William M. Briggs

Statistician to the Stars!

The Preponderance Of Evidence Criterion Is Absurd

She said, he said.

She said, he said.

Our beneficent government, through its Department of Education’s Office of Civil Rights “sent a letter to colleges nationwide on April 4, 2011, mandating policy changes in the way schools handle sexual assault complaints, including a lowering of the burden of proof from ‘clear and convincing’ evidence to a ‘preponderance’ of evidence. Not surprisingly, there has been a marked increase in women coming forward with such complaints.”

The preponderance of evidence criterion is asinine and harmful and bound to lead to grief. Here’s why.

Suppose a woman, Miss W, instead of going to the police, shows up at one of her university’s various Offices Of Indignation1 & Diversity and complains she was “sexually assaulted” by Mr X, a fellow student. By means of a lengthy and secretive process, Mr X is called eventually to deny the claim. He does so.

Incidentally, we may as well inject here the advice that if celibacy outside marriage were promoted at colleges, while the success rate of this program would never reach 100%, any rate above 0% solves for its dedicated individuals the sorts of problems discussed below.

Anyway, ignoring all other details, here is what we have: Miss W says Mr X did it, and Mr X denies. Using only that evidence and none other, there is to the neutral observer a 50-50 chance Mr X did the deed. Fifty-fifty does not a preponderance make, which is any amount over 50%. But since we start at 50% given she-said-he-said, it takes only the merest sliver of additional evidence to push the probability beyond 50% and into preponderance.

What might that evidence be? Anything, really. A campus Diversity Tzar might add to Miss W’s claim, “Miss W almost certainly wouldn’t have made the charge if it weren’t true”, which brings the totality of guilt probability to “almost certainly” (we cannot derive a number). Or the Tzar might say, “Most men charged with this crime are guilty”, which brings the guilt probability to “nearly certain”—as long as we supply the obvious tacit premises like “Mr X is a man and is charged with this crime.”

But this is going too far, and, depending on the university, our Tzar knows she might not be able to get away with such blanket statements. Instead she might use as evidence, “Miss W was crying, and victims of this crime often or always cry”, or “Miss W told another person about Mr X’s crime, which makes it more likely she was telling me the truth as telling more than one person, if her story is a lie, would be to compound a lie.”

Now none of these are good pieces of evidence; indeed, they are circumstantial to the highest degree. But. They are not completely irrelevant premises, either. As long as we can squeeze the weest, closest-to-epsilon additional probability from them, they are enough to push the initial 50% to something greater than 50%.

And that is all we need to crush Mr X, for we have reached a preponderance of evidence. Of course, Mr X may counter or cancel this evidence with his own protestations, or even physical proof that he was nowhere near the scene in question, or that Miss W drunk-texted him first and asked for the services which she later claimed were “assault.” But the Tzar, having all the woes of all feminine society on her mind, is free to ignore any or all of all this.

Mr X, guilty or innocent, is therefore easy to “prove” guilty using this slight standard. He can then be punished in whatever way thought appropriate by the university.

That brings up another question. Suppose you gather all the relevant evidence and decide that the chance of the zombie apocalypse is just under 50%. Or again, given reliable premises you calculate the probability that the woman who just winked at you from across the bar does not have Ebola is 49.999%. You therefore decide that since the preponderance of evidence is against both propositions, you needn’t protect yourself.

You have it. The probability of 50% is in no ways the probability to use for all yes-no decisions. Decisions have consequences and these must be taken into account. Should we wreck a man when the evidence against him amounts only to 50.001%? Too, if we use in every situation the preponderance criterion, the number of mistakes made will be great.

This is why in actual criminal courts, where the standards of evidence are in play and the accused is allowed to confront his accuser and so on, the standard is guilt beyond reasonable doubt, a sane and sober principle.

—————————————————-

1The indignation quip came from this.

17 Comments

  1. So I see that things go every day worse not only in Italy… Thanks for your mission.

  2. False complaints — interesting article, from Slate of all places:

    http://www.slate.com/articles/double_x/doublex/2014/09/false_rape_accusations_why_must_be_pretend_they_never_happen.html

    Here’s a famous case, that’s dragged on for a long time, where the “preponderance of evidence” criteria was clearly wrong:

    http://www.washingtonmonthly.com/college_guide/blog/the_aftermath_of_the_duke_lacr.php and this interesting following with a key witness: http://jezebel.com/woman-who-accused-duke-lacrosse-players-of-rape-convict-1470641733

  3. You must be part of the “war on women”. Demanding that the standards of evidence be the same for men as women simply does not repair the historical inequities women have suffered through the ages at the hands of the oppressing male totalitarian regime. I demand women reparations!

  4. Sander van der Wal

    October 27, 2014 at 10:33 am

    There is of course that old-fashioned institute of chaperoning. But now the guy takes a chaperone with him. Could be a business opportunity.

  5. I guess “preponderance of evidence” is a step up from “the seriousness of the charge”.

  6. The essay is in response to a 2011 (or thereabouts) Congressional amendment to Title IX, Clery Act, which has prompted ongoing consternation for a number of legal questions:

    Congress, apparently, expressly rejected the “preponderance of evidence” standard for on-campus sexual assault cases–but the Obama Administration has been pushing that standard anyway (many on-line reports, e.g.: http://www.aacrao.org/resources/resources-detail-view/campus-safety-rulemaking-panel-debates-standards-of-evidence

    Thus, one issue of concern is an administrative branch of government imposing law contrary to Congress.

    Also, the preponderance standard of evidence IS & has been widely used & applied in civil cases — a lower standard of evidence for the least damaging/costly matters seems reasonable.

    However, sexual assault is a very serious crime, possibly felonious — so why the much lower standard is being pushed is contrary to established legal due process (e.g. see http://legal-dictionary.thefreedictionary.com/Preponderance+of+Evidence ).

    A non-lawmaking government body imposing a mandate to apply Federal legal principles contrary to established practice, and in a manner that bypasses/ignores the Federal lawmaking authority is a cause for concern.

  7. Willis Eschenbach

    October 27, 2014 at 2:35 pm

    It is a total mystery to me why on this lovely planet of ours colleges and universities are adjudicating criminal acts. Rape is a crime. If a woman (or a man) is raped, they need to take their case to the courts. We have them set up for this very reason.

    I would think that an inventive lawyer somewhere should be able to come up with a constitutional or other legal reason that ANYONE who sets themselves up to try, convict, and punish people for breaking the law should go to jail themselves. That is the business of the courts, and the courts alone, not some jackwagon kangaroo court where the judge, the jury, and the prosecution are all the same few people.

    What’s next? High schools trying shoplifting cases ?

    If a crime was committed, then LET THE COURTS HANDLE IT. Colleges and universities have no business setting themselves up in this manner.

    Grrrr …

    w.

  8. Sheri’s comment fits right in what I’ve been waiting to note:

    I guess “preponderance of evidence” is a step up from “the seriousness of the charge”.

    Why should sexual assault face a higher burden of proof than Global Warming especially when consider the seriousness of both if they are true. The cost of assuming their truth is minimal compared to the cost if they are true, right?

    Precautionary Principle, right? Protect women from men [or themselves].

  9. I’m interested in your thoughts in the last few paragraphs. “Decisions have consequences and these must be taken into account” is essentially a restating of the weak version of the precautionary principle, correct? We wear seat belts even though we don’t think we’ll crash our car, we don’t walk alone at night in a bad neighborhood. If we believe that there’s a 9 out of 10 chance that we’ll be fired tomorrow, we look for new work.

    If I understand it, we have to argue against the evidence when people use the precautionary principle? Similar to this: http://wmbriggs.com/blog/?p=12084

    We have people arguing essentially from a “somebody might get hurt” view – “a guilty person might get free.” The only way this can be answered is “yes, but it is more important to not ruin an innocent person’s life”.

    Given that the answer is often not enough for progressives, who can’t make Utopia without stamping the bootheel down on a man as an example to others, what is left for us to do?

  10. Briggs

    Am I correct or incorrect in associating Pascal’s Wager with the Precautionary Principle. When I check our old friend Wiki-Pedia, there is NO cross-reference between the two concepts.

    It’s like they want to dissociate the two concepts

  11. John B: (I know I’m not Briggs, but maybe this will answer your question)
    Variations of this argument may be found in other religious philosophies, such as Islam, Hinduism, and even Buddhism (see below). Pascal’s Wager is also similar in structure to the precautionary principle.
    http://psychology.wikia.com/wiki/Pascal's_Wager
    (wiki is not our friend, by the way)

    Nate: As far as I understand, the precautionary principle is used when there is little or no evidence. It’s the idea that we have an hypothesis that we all might die because of some suspected harm (chemicals, CO2, non-organic produce) could kill us all. We are not going against the evidence. Wearing a seat belt has evidence that it helps in a crash and people do crash, with no way to predict who will crash. Walking alone at night in a bad neighborhood also has evidence to back up the likelihood we would have a bad encounter. If the chances are 9 out of 10 you will lose your job, then you are following the evidence.
    Now, let’s say we think CO2 is killing us all and we have to stop burning fossil fuels. This is a theory with very little evidence. There are gaps everywhere in it. Shutting down CO2 usage is virtually guaranteed to destroy economies, start wars over limited resources, etc. We have plenty of historical evidence for this belief. However, the precautionary principal would say that the CO2 is going to be worse, we are pretty sure, kind of sure……Translation, very little evidence. The only way to sell this is to terrify people into believing we are killing the planet and appeal to emotions. The evidence doesn’t hold, at least not for using the draconian measures often suggested. Yet we are told we must take action.
    As for progressives, the only thing you can do is tell the truth, reveal the science, preach the science and point out the errors. Many will not listen, but unless you’re willing to come up with an equally terrifying future scenario, you won’t win. If you’re willing to paint progressives as the devil incarnate and are better at your version than they are with their version of the future, you might “win”. But for what? People are still running on raw emotion and science is irrelevent. You just reach those who will listen.
    (Sorry so long. Couldn’t find a way to condense it.)

  12. I think Pascal’s Wager is different because there is arguably little “cost” to believing in God. The Precautionary Principle is often abused as being stated with the intent that a cost/benefits analysis is unnecessary.

  13. Sander van der Wal

    October 27, 2014 at 5:59 pm

    i’m with Tom Scharf om the “cost” aspect of Pascal’s Wager. Imagine you have two competing religions, believing in one and following that religions rules results in an afterlife in Hell when the other happens to be true, and vice versa.

    It is easy to see that in such a situation you will choose the religion to believe in that promises the worst afterlife for the unbelievers.

  14. Tom, “I think Pascal’s Wager is different because there is arguably little “cost” to believing in God.”

    What is the argument that you refer to? How do you make yourself believe in something? Can you make yourself believe in anything? I also have this feeling that the majority of religions demand much more than a simple statement of belief.

  15. Scotian,

    I’m not really going to go further than a generalization here. I interpret the wager as only professing belief and following a set of rules (e.g. 10 commandments) that many people follow anyway even if they are unaffiliated.

    Of course the specific God in question and his specific set of rules for admittance to paradise might need a cost/benefits analysis.

  16. Little cost to believe in God?

    The problem I’ve always had with “Pascal’s Wager”, is that very assumption! Let’s ONLY assume the Christian faith belief in God against simple disbelief in God (never mind the myriad of other faiths). Take those innocuous Ten Commandments (which people “naturally follow”). The very 1st Commandment is difficult even for professing Christians. Money, Wife and Children (not to mention Self) often take precedent over and above God and are interrelated.
    (How does one actually Love God with only a reticent “OK, if I have to” belief in God?) The last one or two about coveting are pretty tough on people as well.
    And then there are the bars that Christ himself raised. Most of these rules are about THOUGHT – not including action or failure to act.

    If belief in God (of any kind) were a cakewalk why would Atheists (often the brunt of Brigg’s posts) object so strongly to that belief in God. (Try one of H P Lovecraft’s gods.)

    No, Pascal’s Wager fails as readily as Precautionary Principle for the very same reason. Without a proper or reasoned analysis, you cannot make such decisions simply based on what you ‘might (never)’ lose.

  17. Willis Eschenbach Neither should the NFL, but that were we are at today. That also why I no longer watch football.

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