Logical fallacies are efforts at critical thinking that have gone wrong, either because the author does not understand reasoning processes well enough to be able to think clearly about an argument he or she is trying to construct or because the author is purposely trying to mislead the listener.

Hasty Generalization - The hasty generalization results from drawing a conclusion based on too little evidence.Ex. - Buffy is in a sorority, and she can't pass her math classes. Therefore, sorority girls are bad at math.

False Analogy - False analogy is based on comparing two things that are superficially alike but don't have enough in common to make a real comparison. When people are drawing false analogies, others often suggest that they are comparing apples to oranges.Both of these books are leather-bound with gold lettering, have over 500 pages, and include color plates, so they must be equally well-written and researched. Have you ever heard that you can't judge a book by its cover? Now you know which fallacy is being referred to.

Begging the Question - Also called Petitio Principii, this fallacy usually includes in its premises the very idea that it is trying to argue for in its conclusion.The Bible is the Word of God because it says it is. (Note that including this argument as a logical fallacy is not an attack on the Christian faith. Whether or not the Bible is the Word of God is a matter of personal faith, not logical argumentation.) This argument goes something like this: The Bible says it is the Word of God. The Word of God cannot be false. Therefore, the Bible is the Word of God. Compare that argument to this one: I am an infallible instructor. An infallible instructor never makes a mistake. Therefore, because I said I am infallible, I never make a mistake.

Non Sequitur - Non Sequitur means 'it does not follow.' This fallacy is also called irrelevant argument.When my uncle is nervous, he eats. My uncle is eating. Therefore, he must be nervous.

Post Hoc, Ergo Propter Hoc - 'After this, therefore because of this' - This fallacy takes two events in time and claims that, simply because one occurred before the other, the first one was the cause of the second. My favorite example: I started working at a certain college in 1985. Over the next few years, the average SAT scores of the incoming freshmen increased. Therefore, my being hired by the college caused the average freshman SAT score to increase.Note that people who purposely use this false cause fallacy often do not state the conclusion. They leave it up to the listener or reader to make the connection.

Red Herring - Imagine that you are trying to get away from dogs that are tracking you through the woods. You decide to stop and drag a big, smelly fish across the trail. That's the red herring: introducing ideas into a discussion to throw others off of their logical reasoning patterns. Red herrings often confuse the issues enough that they never get truly resolved. (Intentional or not, this happens a lot in committee work. You can help save a committee time by keeping your eyes open for these red herrings.)The Senator wants us to pass a bill for more funding for education. But why should we pass that bill when he's cheating on his wife? Red herrings often consist of sensational, gossipy types of information or else take an alarmist approach, claiming that an entirely different issue is so pressing that it must be considered at the same time as the original issue or instead of it.

Ad Hominem - The book's example is the ad hominem abusive, "attacking the man."Senator Bow-wow couldn't possibly be a good legislator because he has had an affair, smokes cigars, and drives an Edsel.

Association - Also, called Guilt by Association, this fallacy assumes that "birds of a feather flock together."Joe can't be trusted because his brother has been charged with tax evasion.

Bandwagon - This argument encourages people to follow the crowd. However, it's often used in commercials to tell people how UNIQUE and clever they will be while they are following the crowd.Everyone else is driving our car and feeling superior. Don't you want to drive the same car as everyone else so that you can feel superior, too? I'm a Pepper; he's a Pepper; she's a Pepper. Wouldn't you like to be a Pepper, too?

False or Irrelevant Authority - False authority is often used in commercials when celebrities are used to pitch products. The question to ask yourself is whether the celebrity is an AUTHORITY on the product. A tennis pro is an authority on tennis equipment, especially preference of rackets and shoes. But is Michael Jordan an authority on the type of underwear men should wear?

Card-stacking - Card-stacking leaves out important information that argues for a different or the opposite conclusion. It is not quite the same as oversimplification because the person who is guilty of card-stacking is purposely omitting information pertinent to the argument. The person who oversimplifies may not be aware of other information, may not have thought the argument through all the way.When a television commercial tells you about how you can get cash fast, it generally doesn't tell you all the hurdles you have to jump in order to get that cash. Likewise, many credit card offers that offer low beginning interest rates don't divulge what your monthly payment will be or exactly how high your interest will go after the initial rate period has expired.

Either/or Fallacy - This fallacy is often used to bully opponents into accepting one solution (the author's choice) over another. It presents only two possible choices in solving a problem, and very often, one of those choices is obviously undesirable. It sometimes borders on being an ultimatum.Stop smoking or die young! This fallacy is also expressed in other fashions:The only way to avoid an early death is to stop smoking.

Taking Evidence out of Context - Unfortunately, this is a common college student error in research writing. Taking evidence out of context can give the evidence an entirely different meaning.A well-known film critic was quoted on the video box for a movie as saying that it was "Terrific." I saw the film critic's review of the movie, which he panned, saying he wondered how such a terrific actor as (name forgotten) could appear in such a bad film. Terrific was the only positive evaluative word that he used in his critique, so the video distributors took that word out of context and put it on their box.

Appeal to Ignorance - This argument says that something must be so because we have no evidence to the contrary. We are ignorant of evidence against it.Europeans used to believe that the world was flat because they had never known anyone to sail around it.

Ambiguity - Ambiguity refers to having two (or more) meanings. Remember ambiguous pronoun reference? Two or more nouns could have acted as the antecedent. Ambiguity in logical fallacies tends to happen on the clause or sentence level, making statements that could be taken two ways.Visiting professors can be boring. Is it the act of visiting a professor in his home or office or the act of sitting in a visiting professor's classroom that can be boring?
Equivocation - Equivocation occurs on the word level more than on the sentence level. Equivocation shifts the meaning of the word within the context of the same argument. Suppose I were to tell you that as students your opinions are important in shaping the direction of this college; then suppose, after you make some suggestions, I tell you that your ideas can't be considered because you are ONLY students. This example begins with the concept of "student as valued customer" and ends with the (incorrect) concept of "student as low-ranking, ignorant person." I would be equivocating on the meaning of the word student, shifting between two different concepts underlying it.

Oversimplification - Oversimplification ignores the complicated issues behind an argument. Very often, only one possible cause for a current situation is addressed rather than addressing the multiple causes that often give rise to a problem.Ex. - If Joe would just stop smoking, he could avoid a heart attack. (If Joe is also overweight and has a high cholesterol number, smoking won't be the only possible cause of a heart attack.)

I. Using television or personal experience, describe two examples of logical fallacies you have encountered. There are always plenty of logical fallacies to be seen, both in public figures' posturing (whether it's an election year or not) and in commercials. To get credit for this choice, you should give the context for the logical fallacy (a commercial for a specific product or a public figure's statement about some issue), report what was said as closely as you can recall, tell what kind of fallacy is represented, and explain why you are saying it is that kind of fallacy.

II. Identify and explain the fallacy in each item below. It is possible that some items can be examples of more than one fallacy. Therefore, explain why you think an item is a particular fallacy.

1. UFO's must exist because no reputable studies have proven conclusively that they do not.

2. I saw a construction worker sitting in the shade, drinking a coke, and reading a magazine. Obviously, construction work must be like a vacation.

3. I just saw my first Tennessee Williams play, The Glass Menagerie. He's the twentieth century's greatest playwright, I'm positive.

4. Water fluoridation affects the brain. Citywide, students' test scores began to drop five months after fluoridation began.
(This incident is real.)

5. A 34-year-old female lawyer working in Washington, D.C., for the federal government was denied permission to take the bar examination to practice law in her home state because she was living with a man who was not her husband. What fallacy is working here?

6. To decrease the number of students who are dropping out of school, all we have to do is pass more students.
Seat belts are the only hope for reducing the death rate from automobile accidents.

7. Medicare is free; the government pays for it from taxes.