Maggie's Farm

Logical fallacies are the sins of the world of reason. Just as with sin in the world of morality, in the world of reason we all fall into fallaciousness sometimes - whether by accident or on purpose. And, like sin, logical fallacy can "work" in the interpersonal world, but it fails against harder realities every time.

The study of logical fallacy is the interesting, backdoor approach to thinking about logic and reasoning. It is difficult for us amateurs to define "logical" except to say that it exists where there is no illogicality - which is a Circular Fallacy. In a rational universe, none of us should be permitted to offer an opinion on anything without first making a study of logical fallacy.

Everyone seems to have their favorite bugaboo fallacies, and everyone also seems to have their favorite fallacies to use in debate, manipulation, persuasion, and discussion. (In politics, outright lying seems often to be the preferred mode of disputation, but we are dealing here with subtler matters: errors of which the user is often not aware, but also the deliberate abuse of logical errors to score points, to persuade, or to bamboozle.)

Here are some of my favorite bugaboos:

1. The Texas Sharpshooter Fallacy: Named after the guy who shoots at the barn wall, then draws a target circle around the hole. A favorite of ambulance-chasers and of the statistically-ignorant. You first locate a random cluster, then seek a "cause" for it. The fact is that patterns can occur randomly, and often do. Known as "data-mining" when done by unscrupulous academic researchers: They throw a ton of data into the computer and ask it to find any correlations it can. That ain't science.

2. The Gambler's Fallacy: If you coin-toss four heads in a row, the odds are higher that the next toss will be a tails. Wrong: Lady Luck has no memory. Still waiting for my Tech stocks to bounce back...eventually they have to, right?

3. Retrospective Determinism: The fallacious notion that because something did happen, it was bound to happen. "9-11 was inevitable because..." Colloquially known as 20/20 hindsight.

4. Cum Hoc Ergo Propter Hoc: Mistaking correlation for causation, or even for a direct relationship. Eg, broccoli-eaters have less cancer, therefore broccoli prevents cancer. Another one of my favorite examples was the government study of hospitals which revealed that the great teaching hospitals had some of the poorest outcomes for open heart surgery. The reason, of course, was that they took on the cases no-one else would or could deal with. Thus the best hospitals had the lowest grades, rendering the entire costly, multi-year project ridiculous.

5. The Fallacy of the Single Cause: The fantasy that events have simple or single  "causes." Eg, "What was the cause of World War One?"

6. Ipse Dixit: Argument from authority rather than from data. Eg, "The New York Times says..." Logically permissible only when God, George Orwell, or G. K. Chesterton is speaking.

All of the above, and many more, can be found in more detail on the links below. I often feel that the most effective fallacious arguments can be made by combining or sequencing two or more fallacies, thus overwhelming the logical capacities and scrambling the brains of your helpless victim. Indeed, they rarely occur in pure form anyway. Sad to say, sometimes one must use fallacies for persuasion - even when cogent logic is on your side - because fallacies can often be more persuasive than fact or logic to the uninitiated (such as jurors, voters, and newspaper readers). Hence the lowly reputations of politicians and lawyers.

Aristotle may have been the first (no surprise there - he was the first to organize everything - an obsessional genius) to list logical fallacies in his Sophistical Refutations, in which he listed thirteen. The delightful website The Fallacy Files is a fine source, and Wikipedia has an exhaustive list, with many pretty good definitions, here. 

"Was Mann Weiss, Mann Sieht." I find that identifying fallacies can be good fun and, once one learns their names, it can be as amusing as bird-watching to silently identify the ones you see and hear everyday. It is more fun to notice the ones others use, but the real trick is to to identify the ones we find ourselves using. Self-deception is a great sin.