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.
This resource covers using logic within writing—logical vocabulary, logical fallacies, and other types of logos-based reasoning.
Contributors: Ryan Weber, Allen Brizee
Last Edited: 2018-01-10 09:57:31
Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.
Slippery Slope: This is a conclusion based on the premise that if A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen, too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. Example:
If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.
In this example, the author is equating banning Hummers with banning all cars, which is not the same thing.
Hasty Generalization: This is a conclusion based on insufficient or biased evidence. In other words, you are rushing to a conclusion before you have all the relevant facts. Example:
Even though it's only the first day, I can tell this is going to be a boring course.
In this example, the author is basing his evaluation of the entire course on only the first day, which is notoriously boring and full of housekeeping tasks for most courses. To make a fair and reasonable evaluation the author must attend not one but several classes, and possibly even examine the textbook, talk to the professor, or talk to others who have previously finished the course in order to have sufficient evidence to base a conclusion on.
Post hoc ergo propter hoc: This is a conclusion that assumes that if 'A' occurred after 'B' then 'B' must have caused 'A.' Example:
I drank bottled water and now I am sick, so the water must have made me sick.
In this example, the author assumes that if one event chronologically follows another the first event must have caused the second. But the illness could have been caused by the burrito the night before, a flu bug that had been working on the body for days, or a chemical spill across campus. There is no reason, without more evidence, to assume the water caused the person to be sick.
Genetic Fallacy: This conclusion is based on an argument that the origins of a person, idea, institute, or theory determine its character, nature, or worth. Example:
The Volkswagen Beetle is an evil car because it was originally designed by Hitler's army.
In this example the author is equating the character of a car with the character of the people who built the car. However, the two are not inherently related.
Begging the Claim: The conclusion that the writer should prove is validated within the claim. Example:
Filthy and polluting coal should be banned.
Arguing that coal pollutes the earth and thus should be banned would be logical. But the very conclusion that should be proved, that coal causes enough pollution to warrant banning its use, is already assumed in the claim by referring to it as "filthy and polluting."
Circular Argument: This restates the argument rather than actually proving it. Example:
George Bush is a good communicator because he speaks effectively.
In this example, the conclusion that Bush is a "good communicator" and the evidence used to prove it "he speaks effectively" are basically the same idea. Specific evidence such as using everyday language, breaking down complex problems, or illustrating his points with humorous stories would be needed to prove either half of the sentence.
Either/or: This is a conclusion that oversimplifies the argument by reducing it to only two sides or choices. Example:
We can either stop using cars or destroy the earth.
In this example, the two choices are presented as the only options, yet the author ignores a range of choices in between such as developing cleaner technology, car-sharing systems for necessities and emergencies, or better community planning to discourage daily driving.
Ad hominem: This is an attack on the character of a person rather than his or her opinions or arguments. Example:
Green Peace's strategies aren't effective because they are all dirty, lazy hippies.
In this example, the author doesn't even name particular strategies Green Peace has suggested, much less evaluate those strategies on their merits. Instead, the author attacks the characters of the individuals in the group.
Ad populum: This is an emotional appeal that speaks to positive (such as patriotism, religion, democracy) or negative (such as terrorism or fascism) concepts rather than the real issue at hand. Often this is an appeal that presents what most people, or a group of people think, in order to persuade one to think the same way. Getting on the bandwagon is one such instance of an ad populum appeal.
If you were a true American you would support the rights of people to choose whatever vehicle they want.
In this example, the author equates being a "true American," a concept that people want to be associated with, particularly in a time of war, with allowing people to buy any vehicle they want even though there is no inherent connection between the two.
Red Herring: This is a diversionary tactic that avoids the key issues, often by avoiding opposing arguments rather than addressing them. Example:
The level of mercury in seafood may be unsafe, but what will fishers do to support their families?
In this example, the author switches the discussion away from the safety of the food and talks instead about an economic issue, the livelihood of those catching fish. While one issue may affect the other it does not mean we should ignore possible safety issues because of possible economic consequences to a few individuals.
Straw Man: This move oversimplifies an opponent's viewpoint and then attacks that hollow argument.
People who don't support the proposed state minimum wage increase hate the poor.
In this example, the author attributes the worst possible motive to an opponent's position. In reality, however, the opposition probably has more complex and sympathetic arguments to support their point. By not addressing those arguments, the author is not treating the opposition with respect or refuting their position.
Moral Equivalence: This fallacy compares minor misdeeds with major atrocities.
That parking attendant who gave me a ticket is as bad as Hitler.
In this example, the author is comparing the relatively harmless actions of a person doing their job with the horrific actions of Hitler. This comparison is unfair and inaccurate.