Logical fallacies are errors in reasoning that are based on poor or faulty logic. When presented in a formal argument, they can cause you to lose your credibility as a writer, so you have to be careful of them.
Sometimes, writers will purposefully use logical fallacies to make an argument seem more persuasive or valid than it really is. In fact, the examples of fallacies on the following pages might be examples you have heard or read. While using fallacies might work in some situations, it’s irresponsible as a writer, and, chances are, an academic audience will recognize the fallacy.
However, most of the time, students accidentally use logical fallacies in their arguments, so being aware of logical fallacies and understanding what they are can help you avoid them. Plus, being aware of these fallacies can help you recognize them when you are reading and looking for source material. You wouldn’t want to use a source as evidence if the author included some faulty logic.
The following pages will explain the major types of fallacies, give you examples, and help you avoid them in your arguments.
The Most Commonly Used Fallacies
A fallacy is an often plausible argument using false or illogical reasoning.
1. Appeal to Pity (Ad Misericordiam) — an argument that appeals to another’s sympathy; not answering the argument
EX: A woman applies to college. When the Admissions Director asks about her grades, test scores, and extracurricular activities, she states that she didn’t have much time to study because her mother has been sick for several years and she has had to work through almost all of high school.
2. Appeal to Ignorance (Ad Ignorantum) — asserting a proposition is true because it has not been proven false
EX: Taking vitamin X is good for you since nobody taking it has become sick.
3. Arguing by Association — an argument used to promote guilt by association
EX: Both Senator Muha and Latin American Marxists are critics of the Chilean government; therefore, Senator Muha must be a Marxist.
4. Argument Backed by a Stick (Force; Argumentum Ad Baculum) — resorting to threat in order to have a point accepted
EX: Our paper certainly deserves the support of every German. We shall continue to forward copies of it to you, and hope you will not want to expose yourself to the unfortunate consequences in case of cancellation.
5. Bandwagon Appeal (Ad Populum) an argument that suggests one is correct if they go along with the “crowd”
EX: Every fashionable senior this year is wearing a piece of Navajo jewelry.
6. Begging the Question (Circular Reasoning) — you report what is true, repeating what you believe, only in different words
EX: I am in college because it the right thing to do. Going to college is expected of me.
7. Contradictory Premises — the points of the argument contradict each other; therefore, there is no argument
EX: If God can do anything, he can make a stone so heavy that He won’t be able to lift it.
8. False Alternative (either/or syndrome) — all other possibilities, explanations, or solutions are ignored
EX: Given the alarming number of immigrants in the U.S. who fail to learn English and speak it, mandating English as the official language of our country must be done.
9. False Analogy — an argument that assumes a fundamental similarity between two things that resemble each other only in part
EX: A college has no right to fire a popular teacher. To do so is like throwing out of office a public official who has just been reelected by the majority of the voters.
10. False Cause (Post Hoc) — this argument equates sequence with causality: Because Event A was followed by Event B, the first caused the second
EX: Every time I wash my car, it rains. I washed my car today; therefore, it will rain today.
11. Half-Truths — an argument that contains evidence that is only partly true
EX: Making English the official language is a good idea because it will make it easier for people to understand one another.
12. Hasty Generalization — this argument assumes “all” are the same, but there are too few instances to support such a claim
EX: John likes Keating’s health plan, Becky likes Keating’s health plan, and Sayd likes Keating’s health plan; therefore, Keating’ s health plan must be the best choice.
13. Hypothesis Contrary to Fact — an argument that starts with an untrue hypothesis and then tries to draw supportable conclusions from it
EX: If I had never met Dan twenty years ago in college, I would never have fallen in love.
14. Oversimplification — an argument that makes simple of a very complex issue by using catchy phrases such as: “It all boils down to...”or “It’s a simple question of...”, etc.
EX: Censorship is a simple question of protecting our children from obscenities.
15. PoisoningtheWell/Personal Attack (Ad Hominem) — an argument that personally attacks another as to discredit the issue at hand
EX: Two students are running for student body president. Prior to the vote, one candidate puts up fliers all over the building indicating that the other boy is a cheater, liar, and has bad grades.
16. Red Herring — think of a stinky smoked fish dragged across the trail to throw a tracking dog off scent; an argument that tends to sidetrack everyone involved
EX: While discussing the need for tobacco subsidies in the federal budget, somebody asserts that all restaurants should have non-smoking sections.
17. Shifting the Meaning of a Key Term (There are two ways of doing this: First through Equivocation [shifting the meaning of one term] and through Amphiboly [shifting the meaning through sentence structure]) — an argument that uses the meaning of words or sentences in two different senses
EX: Criminals do everything to obstruct arrest, prosecution, and conviction. Likewise, liberal lawyers try in every way to obstruct the work of police. Obviously, then, most liberal lawyers are no better than criminals themselves. (Amphiboly)
18. Slippery Slope — the assumption that if one thing is allowed, it will only be the first in a downward spiral of events
EX: If you continue to watch professional wrestling, your grades will drop, you will become violent, and eventually you will end up in jail.
19. Sweeping Generalization (Dicto Simpliciter) — an argument based on an unqualified generalization
EX: All high school students are irresponsible.
20. Shameful Argument (Argumentum Ad Verecundium) — appealing to an authority in one field regarding something in another field in which that authority has no more standing than anyone or anything else
EX: The policeman testified on the witness stand that the cause of death to the victim was a bullet wound that entered the body at the sternum, penetrated the left lung and lodged at the 5th lumbar vertebrae.