Wednesday, November 28, 2012

Logical Fallacies: Cherrypicking

            I used to make videos about logical fallacies, but then I took an arrow to the knee.
            A while ago, I made a cursory study of economics, and in this, there were a few books I found quite helpful; among them, Economic Literacy by Jacob De Rooy, Economics for Dummies by Sean Masaki Flynn, and The Undercover Economist by William J. Harford.  I found them helpful because of the pattern they followed.
            "Here we have term A, here's what it means, and here's what it amounts to.  Here we have term B, here's what it means, and here's what it amounts to.  Here we have term C, here's what it means, and here's what it amounts to.  Now let's look at how concept A, concept B, and concept C relate to one another."
            Other books on the subject I found not so helpful.  Basic Economics and Applied Economics, both by Thomas Sowell.  These followed a different pattern.
            "Here we have an instance in which increased government regulation was followed by bad events.  Here we have an instance in which decreased government regulation was followed by good events.  Here we have another instance in which increased government regulation was followed by bad events.  Here we have another instance in which decreased government regulation was followed by good events."
            Clearly, this fellow is trying to support (without actually making) the claim that more regulation is intrinsically a bad thing and less regulation is intrinsically a good thing, without exception.  First, in omitting any of the downsides of the instances in question, he is counting on us to assume that there were none.  Second, in carefully selecting the instances he relates (his anecdotes), he is trying to support this conclusion—this correlation—with purely anecdotal evidence.  These two problems we run into even if we assume that each of these anecdotes are related accurately which could be a pretty big assumption to make.
            Consider a popular practice at white supremacist rallies.  A presentation is made, and it begins with various slides and anecdotes of someone who just happens to be black and just happens to have a history of violent, gruesome crime; the more gruesome, the better.  This continues for twenty minutes and then it switches to a litany of slides and anecdotes of another such person who also happens to be black and to have a history of violent, especially heinous crime.  This practice continues for three straight hours, switching to a different person every twenty minutes.  Interestingly enough, each person they talk about just happens to share these two characteristics; being black and having a history of violent, horrifying crime.
            The accounts of violence disgust and horrify the audience, and since each person they are shown while in this state of disgust and horror just happens to be black, they learn to associate the two characteristics.  After this, seeing someone ethnically African will have a tendency to bring them back to this state, as per Classical Conditioning, especially if such is not an everyday occurrence.
            The idea in this case is to get the audience to accept that, since such is the case in 100% of the cases presented, such is the case 100% of the time.  Instances of this can usually be identified when someone hates a certain party with a passion and can’t explain why.  The reason they hate this party is not because the party in question has necessarily done anything wrong but because they have been trained to associate this party with all manner of horrifying things and so experience horror every time this party comes up.  Of course, they tend to have trouble understanding why others don’t experience the same horror.
            Ann Coulter once made a presentation in which she listed one terrorist attack which just happened to have been carried out by Muslims, and then another terrorist attack which just happened to have been carried out by Muslims, then another and another, and then she referred to this as a "100% correlation," counting on her audience to conclude that, since such is the case in 100% of the accounts she has related, such must be the case 100% of the time.
            Omitting one or just a few important details in a misleading manner is known as a lie by omission, but continuously, deliberately including the details that support a certain conclusion while deliberately excluding the ones that go against it, counting on your audience to assume that the details that go against it don't exist is known as cherrypicking.
            It's cherrypicking when one selects the evidence which appears to support one's conclusions while overlooking the evidence that goes against it.  It's like confirmation bias, but deliberate.  One form of cherrypicking is the act of trying to demonstrate a correlation with what is known as anecdotal evidence, so I'll take a moment to talk about that, specifically.
            I've known a few people in my day with fairly dark eyes and fairly light hair.  I've also known a few people with whom it was the other way around.  If I were to go searching, surely, I could find quite a number of such people in the world.  Would this prove that such is the norm?  Of course not, but why not?
            Because correlations are not established by cherry-picked anecdotes.  A key consideration in correlation is percentage.  What percentage of the time do the two characteristics in question go together?  If you are not keeping track of both the percentage of the time they do and the percentage of the time they don't, you are clearly not striving to answer this question, so you are not establishing correlation.
            Correlation, however, does not establish causation, but that is a subject for a different video.