Posted by: W. E. Poplaski | February 12, 2009

Critical Thinking: Fanciful Fallacies

“How you doin’ out there?

Y’ever seem to have one of those days where it just seems like everybody’s gettin’ on your case, from your teacher all the way down to your best girlfriend? Well, y’know, I used to have ’em just about all the time. But I found a way to get out of ’em.

Let me tell you about it!” *


First thing y’gotta do is get ya head on straight.  And, you do that with good critical thinking skills, which you can practice everyday in the boy’s room or anyplace else you choose (of course, some of you might prefer the girl’s room).


Ok, so maybe you are not ready to use logic at the level of a Whitehead, Russell or Hume—especially not in the restroom.  But, you can easily eliminate some of the faulty reasoning from your thinking, and try to spot it in other people’s arguments, too.


Start your journey to good critical thinking by looking out for these common miscreants of fallacious reasoning:


Red Herring.  A red herring is a deliberate attempt to divert an argument by changing the subject.  Example—“You know, I think we should vote ‘guilty’. I’m tired of people thinking they can do as they please. I say, vote guilty, and they will know we mean business.”  The need to affect people’s behaviors is a very different argument than a person’s guilt of a particular crime.


Ad Hominem (Argument against the person). An ad hominem reply to an argument attacks the source of an argument rather than its substance. Example—Jack: I don’t think it’s safe to go up that hill; it’s just too slippery after all of that rain.  Jill: Oh, what do you know; you had to repeat 4th grade three times!


Slippery Slope.  A slippery slope argument asserts that one event (A) leads to another (E)—i.e., starting on a particular course of action will result in sliding down a slope to ruin—ignoring the possibility that intervening steps (for example, B, C, and D), however unlikely they may be,  also must occur to get to (E).  It is a faulty use of the if-then operator.  Examples—“If I make an exception in your case, then I will have to do it for everyone else, too.” “If I give him an inch, then he will take a mile.” “If we legalize marijuana, then the next thing you know we’ll be legalizing heroin and crack cocaine.”


Cum Hoc, Ergo Propter Hoc (With this, therefore because of this).  This fallacy is a failure to recognize that correlation does not imply causation.  Example—there is a strong correlation between the consumption of ice cream and drownings; therefore, ice cream consumption causes drowning (however, note that when the temperature becomes hot, more people eat ice cream and more people also take to the water, with a resultant increase in drownings). There are three ways in which a correlation (e.g., between ‘A’ and ‘B’) might not reflect causation:  (1) a lurking variable may be involved—as was the case with ice cream and drownings—(2) the direction of causation may be the opposite of your conclusion (‘B’ may cause ‘A’ rather than the other way around), and (3) the correlation may simply be a coincidence.


Argumentum ad Ignorantiam (Appeal to ignorance). An appeal to ignorance is an argument against or for a proposition on the basis of a lack of evidence against or for it.  Example—“The lake looks completely frozen—I don’t see any spots of open water—so the ice must be thick enough to play our hockey game safely.” However, note that the absence of evidence the ice is unsafe, does not mean that it is in fact safe; it still could be too thin to support any weight.


Those five miscues of reasoning are only a small sampling of how thinking can go wrong.  Check out these websites for further examples:

Also, see


* [With apologies to Michael “Cub” Koda (1948 – 2000) and Brownsville Station]


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