Monday, December 5, 2016

The Null Hypothesis

We now live in a post-truth, post-fact universe facilitated by social media and a gullible public. One in which real-life gunmen come to pizzerias with assault rifles on preposterous online allegations of a "child-sex ring," and local assemblywomen accuse black Muslim electricians of running "Islamic terrorist compounds" in the Mat-Su Valley with zero evidence.

Accordingly, I think it's time to revisit the concept of "the null hypothesis." John Aronno at Alaska Commons (link above) correctly called out the "Islamic Compound" story propagated by Anchorage Assemblywoman Amy Dembowski as "fake news," and a commenter on his article said this:
This article appears to me to be nothing more then media disinformation. As is generally the case now when somebody’s cleaning [sic.] fake news they’re just using that term to discredit information that they did not want to become common knowledge. Due to the fact that this article provides no hard facts disproving Demboski’s claims I have to say any critical thinking reader would have to call a Pinocchio. 
Actually, "any critical thinking reader" would do just the opposite, and here's why:

We all know that a lie gets halfway around the world before the truth can get its boots on, and the internet has given new life to that idiom. The same sort of argument was made about Donald Trump's "millions of people voted illegally" claims--that someone should prove these allegations false, rather than the other way around--that the person making the allegations has the burden to prove they are true

Enter the null hypothesis.

One of the first things you learn in law school is who has the burden of proof in any given case. Usually, the person making the allegation (e.g. a prosecutor or plaintiff's attorney) has the burden to prove their claim by some degree of evidence--say, a preponderance of the evidence in civil cases, or beyond a reasonable doubt in criminal trials.

In science as in law, the concept of whose role it is to prove facts comes down to the theory of the null hypothesis. It's a bit more complicated than this, but in basic terms the concept is that generally speaking, you cannot prove a negative.

In other words, the absence of evidence is not evidence of absence, but nor does that vacuum allow for the proof of a negative or shift that burden of proof somehow. For example, if a person is color blind and can't distinguish between red and green, that is not evidence that the colors red and green do not exist. That is an impossible thing to prove.

That said, in his 1953 book Introduction to Logic, Irving Copi wrote:
In some circumstances it can be safely assumed that if a certain event had occurred, evidence of it could be discovered by qualified investigators. In such circumstances it is perfectly reasonable to take the absence of proof of its occurrence as positive proof of its non-occurrence.
When we as a society demand that people responding to ridiculous allegations disprove "facts" rather than require the person making the allegations to affirmatively prove them, we are ignoring fundamental precepts of logic. Words and logic--and the link between them--matter and have real-life consequences. If we continue to ignore that reality, someone is eventually going to get hurt or killed.

Image result for rubik's cube image

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